A parchment-lined square pan of tan shortbread cut into fingers, flecked with brown butter specks and a few salt flakes, beside a small pale saucepan of browned butter

Brown Butter Shortbread, and the Water You Have to Put Back

Brown butter shortbread does its toasting in a saucepan. The dough goes into the same low oven as a classic Scottish slab and comes out only a shade darker, the color of wet sand, yet it tastes of toffee and hazelnut from the first bite. All of that flavor was made ten minutes before the flour came out of the cupboard, when a pan of butter foamed, went quiet and dropped a sediment of brown flecks. If you have never made the plain version, the pale shortbread recipe is the one to learn first. This one is for the cook who has, and wants the butter to taste cooked.

The catch is the water inside the butter, roughly one-sixth of its weight. The international Codex standard for butter allows up to 16 percent, and the University of Wisconsin's Center for Dairy Research puts ordinary butter at 16 to 17.5 percent. In plain shortbread that water is the only liquid in the dough, held in droplets so fine that nobody thinks of it as an ingredient. Browning boils all of it off, and the noisy spitting at the start is the sound of it leaving. Two sticks go into the pan at 227 grams and come out at around 190.

Browning spends that water to buy flavor, and shortbread without its water gets shorter still. Wheat proteins need water before they can link up into gluten, a point Harold McGee makes in On Food and Cooking, and in a dough with almost none the flour stays loose. Mixed with no water at all, brown butter dough tends to stay a heap of damp sand that will not hold when pressed, and it bakes into fingers that break as you lift them. So the recipe keeps a small ledger. It browns a little more butter than the classic 1:2:3 recipe uses and scales the sugar and flour to the fat that survives, lets the browned butter set back into a soft solid, and returns one tablespoon of cold water when the flour goes in. A second tablespoon waits in reserve for dry flour.

What happens in the pan

As long as there is water in melted butter, the butter stays close to the boiling point of water, because the heat goes into making steam, as McGee explains. That is the long first stage: big bubbles, spitting, a thick foam on top. When the sputtering fades and the foam turns fine and pale, the water is nearly gone and the temperature starts to climb quickly. The milk solids, the one or two percent of butter that is mostly protein and milk sugar, have sunk to the bottom by now, and they begin to brown in Maillard reactions, the family of reactions behind bread crust and seared meat that the Maillard and caramelization explainer walks through. Watch the flecks.

Stop at hazelnut. The flecks should be the brown of a toasted hazelnut skin, and the smell shifts from warm milk to something nutty, like toasted hazelnuts. The French name, beurre noisette, means hazelnut-colored butter; no hazelnut is involved. Go much further and the specks turn black and the smell goes sharp and acrid. A review of butter aroma research by Silvia Mallia, Felix Escher and Hedwig Schlichtherle-Cerny notes that high-temperature treatment of butter can develop off-flavors. Burnt butter can't be rescued, so start again. Pour the butter into a cool bowl the moment it is ready, because a hot pan keeps cooking it.

Heating creates aromas that fresh butter lacks. The same review lists a potato-like compound called methional among them, along with a furanone that smells of caramel. A 2013 review by Wilfried Schwab in the journal Molecules describes the same molecule, known by the trade name Furaneol, as an aroma compound that strawberries and many other fruits make naturally, and records that it was first reported in 1960 as a product of Maillard browning. Part of the caramel note heated butter develops comes from a molecule that a ripe strawberry also makes on its own.

Getting the butter solid again

Liquid brown butter makes a slack, greasy dough that bakes with oily, slumped edges. It has to go back to the cool, dentable state that plain shortbread starts from. Refrigerate it in its bowl and stir every 15 minutes or so. The flecks sink, and stirring keeps them spread through the fat while it sets. After about an hour it turns from translucent to opaque and thickens to the texture of soft butter, and that is the moment to use it. If it has gone firm around the edges, beat it for a few seconds or leave it on the counter for 15 minutes. You can brown and set the butter the day before and let it soften on the counter before mixing.

Ingredients

  • 227 g (1 cup, 2 sticks) unsalted butter, to be browned
  • 110 g (1/2 cup plus 1 tablespoon) superfine (caster) sugar, plus 1 tablespoon for the top
  • 1/2 teaspoon fine sea salt (1/4 teaspoon if browning salted butter)
  • 1/2 teaspoon vanilla extract (optional)
  • 320 g (2 1/2 cups) all-purpose flour
  • 1 to 2 tablespoons cold water
  • A few flakes of sea salt for the top (optional)

You need a light-colored saucepan, so you can see the flecks change color, and an 8-inch (20 cm) square light metal pan. Superfine sugar has finer crystals than regular granulated sugar, so it disappears into the butter with less beating. Vanilla is optional; if you use it, half a teaspoon is enough (shop Burlap & Barrel Vanilla Extract).

Method

  1. Brown the butter. Cut the butter into pieces and melt it in the saucepan over medium heat. It will foam and spit loudly at first; swirl the pan now and then. When the noise dies down and the foam turns fine, stay with it. Within a minute or two the specks on the bottom go from pale tan to hazelnut brown and the kitchen smells of toasted hazelnut and toffee. Take it off the heat and pour it into a heatproof bowl straight away, scraping the pan so every fleck goes in. Six to eight minutes in all. If you have a scale, weigh it: about 190 g is normal.
  2. Let it set. Refrigerate the bowl, stirring every 15 minutes, until the butter is opaque and soft enough that a fingertip leaves a dent, about an hour. (For a faster set, stand the bowl in ice water and stir constantly for 10 to 15 minutes, watching closely.) Meanwhile line the pan with parchment, leaving an overhang on two sides to lift it out.
  3. Beat briefly. Beat the set brown butter with the sugar, salt and vanilla on low speed, or with a wooden spoon, for about a minute, only until the sugar vanishes. Beating in air makes shortbread puff and turn cakey, so stop while the mixture still looks dense and glossy.
  4. Add the flour, then the water. Add the flour and mix on the lowest speed until the mixture looks like damp sand with no dry patches. Sprinkle a tablespoon of cold water over it and mix for a few seconds. Squeeze a handful. If it holds its shape, stop. If it falls apart, add the second tablespoon and mix again only until it clumps. Water is what lets gluten form, so the less mixing it gets after the water goes in, the more tender the slab.
  5. Press, prick, chill. Press the dough into the pan in an even layer, pushing into the corners, and smooth the top with the flat base of a glass. Prick it all over with a fork right down to the pan, in rows about an inch apart, so steam can escape and the slab stays flat. Press a few salt flakes onto the surface if using. Chill 30 minutes while the oven heats to 300°F (150°C).
  6. Bake low and ignore the smell. Bake 45 to 55 minutes. Plain shortbread is judged partly by the buttered-toast smell that means it is nearly done, but this dough smelled of toast before it went in and started out tan, so neither the smell nor the color tells you much. Look at the surface. It turns from satiny to dry and matte, the edges pull faintly from the pan and go one shade darker than the middle, and the center feels firm under a fingertip. If the middle still feels soft or looks damp, give it five more minutes.
  7. Cut warm, cool completely. Rest the pan 10 minutes, then cut 16 fingers with a thin knife, pressing straight down. Scatter the reserved tablespoon of sugar over the top and leave the fingers in the pan until completely cold. They are soft when warm and turn crisp as they cool, and they crumble if lifted too soon. In an airtight tin they keep for about a week.

When it goes wrong

What you see Likely cause Next time
Bitter, acrid edge; black specks in the crumb The butter went past hazelnut, or kept cooking in the hot pan Use a light pan so you can see the flecks, and pour the butter out the moment it smells nutty
Tastes like ordinary shortbread Browning stopped at pale tan, or the flecks stayed in the pan Wait for hazelnut-brown flecks and scrape every one into the bowl
Greasy top, slumped or oily edges The butter was still liquid or translucent when mixed Let it set until opaque and dentable; chill the pressed slab the full 30 minutes
Dough will not hold; fingers crumble when lifted Not enough water to replace what browning removed, or very dry flour Add the second tablespoon of water, press firmly, and leave the fingers in the pan until cold
Hard and tough Too much water, or too much mixing after the water went in Add water a tablespoon at a time and stop mixing as soon as a squeezed handful holds
Pasty center, floury taste Underbaked; the tan color made it look done early Judge by a matte top and a firm center, not color
Shatters along its own lines Cut after cooling Cut 10 minutes out of the oven

Baking it in Denver

Two things change at Denver's elevation, and this recipe leaves the oven where it is. Colorado State University Extension puts the boiling point of water at 203°F at 5,000 feet, against 212°F at sea level, and Denver sits a little higher still, so the sputtering stage runs cooler. The cues work the same, because the flecks brown only after the water is gone. The bigger change is the flour. CSU Extension notes that flour is drier and absorbs more liquid in a high, dry climate, and this dough is already short of water, so expect to use the second tablespoon. CSU's cookie advice includes a slight cut in fat or sugar, a little more liquid and flour, and a slightly hotter oven; its larger 15 to 25°F increase is for cakes, to set the batter before it over-rises. An unleavened slab pressed into a pan has no rising batter to set, and a hotter oven would mostly darken a dough that starts out tan, so this recipe stays at 300°F. The rest of the city's baking adjustments are in the Denver altitude cooking guide.

Where a butter biscuit gets its color

Line up three butter biscuits and each one has taken its color from somewhere different. Scottish shortbread, eggless and baked low, barely colors at all, so it tastes of fresh butter and dried wheat. The Breton sablé bakes to gold in the oven, and the classic recipes put egg yolk and salted butter in the dough. Filet Bleu's palets bretons (shop Filet Bleu Palets Bretons) are an easy Breton biscuit to put on the plate for comparison, and the Filet Bleu producer guide tells the company's story. Brown butter shortbread is the third case. Its color and its toasted flavor were made in the saucepan, and the oven only has to dry the dough. That makes it a French sauce-cook's technique inside a Scottish biscuit, and French pastry already uses brown butter this way: the financier, the small almond cake, is classically made with beurre noisette.

Putting it on the table

Brown butter carries salt well, and a few broad flakes on top give a sharp bite now and then against all that toffee. Maldon (shop Maldon Sea Salt) is one broad flake to use, and the flaky sea salt guide explains why a flake's shape changes how it tastes. With tea, a strong black cup cuts the richness; Mariage Frères English Breakfast (shop Mariage Frères English Breakfast) is one to try, and the English Breakfast tea guide covers how to brew it. For a small dessert plate, Fruition makes a Brown Butter milk chocolate (shop Fruition Brown Butter Milk Chocolate) to set beside a finger or two.

The shop is at 263 Josephine Street in Cherry Creek, Denver, where visitors can ask staff questions, and products ship nationwide from theambrosianpantry.com.

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