Ingredient

Butter

Butter is an emulsion: roughly four-fifths fat, most of the rest water, and a small amount of milk solids. Almost everything butter does in cooking — the foaming, the browning, the burning, the flakiness in pastry — follows from those three parts behaving differently under heat.

Three ingredients in one block

Put butter in a hot pan and it foams. That is the water boiling off. Once the foaming stops, the fat is much hotter and the milk solids — the proteins and sugars — start to brown, giving the nutty smell of beurre noisette. Shortly after that, they burn, and the black specks taste acrid.

Oil does none of this because oil is only fat. It is why butter has a much lower usable temperature than its fat alone would suggest, and why the classic trick of adding a little oil to the pan works: the oil dilutes the solids and buys you a wider window before they catch.

The forms

Salted

For the table, for toast, and for savoury cooking where you would be adding salt anyway. The salt content varies between brands, which is why baking recipes avoid it.

Unsalted

The baking default, because it lets the recipe control the salt. Also usually fresher, since salt is a preservative.

Clarified butter

Melted and separated so only the fat remains. No water, no solids, so it will not burn at ordinary frying temperatures and keeps far longer.

Ghee

Clarified butter cooked a little further, so the solids brown before they are removed. Nutty, and a staple fat in Indian cooking.

Cultured butter

Made from cream that was allowed to ferment first. Tangier and more complex; worth it where you taste the butter directly.

Browned butter

Cooked until the solids toast. A flavour ingredient, not a cooking fat — make it, then use it.

Temperature is the whole of baking with butter

A recipe telling you the state of the butter is not being fussy; the state determines the result.

• Cold and cubed for pastry, scones and crumble. Solid pieces of fat stay separate in the dough, then melt in the oven and leave layers and pockets. Warm butter smears and gives you something dense.
• Soft but not melted for creaming with sugar in cakes. You are beating air into the fat, and fat that is too cold will not take it while fat that is melted cannot hold it.
• Melted for brownies, some muffins and most quick breads, where you want a dense, fudgy result rather than an aerated one.
• Frozen and grated is the reliable trick for rough puff and flaky scones, giving you cold pieces evenly distributed without overworking the dough.

Making browned butter

Two minutes of attention that transforms biscuits, cakes, pasta sauces and anything with sage in it.

1. Melt butter in a light-coloured pan — you need to see the colour, which is why a black pan makes this harder.
2. Let it foam. That is the water leaving, and you cannot rush it.
3. When the foaming subsides, watch closely. The solids at the bottom will go from pale to gold to hazelnut brown in well under a minute.
4. The moment it smells nutty and the specks are properly brown, pour it out of the pan into a cold bowl. Left in the hot pan it will keep cooking and burn.
5. Use the solids as well as the fat — they are where the flavour is.

Making it, and what comes off it

Butter is one of the few things in a shop that is genuinely easy to better at home.

• It is over-whipped cream. Keep whipping past stiff peaks and the fat coalesces and the buttermilk separates out. Ten minutes in a mixer.
• Wash it properly. Knead the butter in iced water until the water runs clear. Buttermilk left in it is what makes home-made butter go off quickly, and this step is not optional.
• Cultured butter — cream soured with live cultures overnight before churning — is tangier and more complex, and it is what good French butter is.
• The buttermilk works in scones, soda bread and pancakes, though it is not the same as cultured shop buttermilk.
• Clarified butter and ghee come from melting it and separating out the milk solids, which raises the smoke point and changes the flavour.

The forms, and when each matters

• Cold and cubed — pastry, scones, crumble. The fat must stay in solid flakes to create layers and shortness.
• Soft (room temperature) — creaming for cakes. It must hold air, which melted butter cannot and cold butter will not.
• Melted — brownies, banana bread, muffins. Denser and chewier results, because no air is beaten in.
• Browned (beurre noisette) — melted until the milk solids toast nut-brown. Three minutes of work and one of the largest flavour improvements available in baking.
• Clarified — milk solids removed, so it can be heated much higher without burning. For frying and for hollandaise.
• Cold, whisked in at the end — for emulsifying a pan sauce or a beurre blanc. It must be cold and it must be off the heat.

Common questions