Actually very easy

Butter

The beliefButter is assumed to be a factory product, and whatever you make at home to be something lesser.

The truthIt is whipped cream taken too far. Around the fifteenth minute it separates on its own and you have both butter and buttermilk.

15 minutes

How to make it

What you need

500 ml full-fat cream, at least 35% fat
Iced water
Salt, if you want it: 1–2% of the weight

How the engine read this list (3 lines)

500 g	Full-fat cream	cream
—	Iced water	water
—	Salt optional	salt

An empty weight means that line could not be turned into grams — either the amount is open ("to taste") or the ingredient has no record here. Neither enters the sum as zero; they do not enter it at all.

Take the cream out and let it come to 10–14 °C — half an hour is enough. Whipped straight from the fridge it will not separate, however long you go.
Whip it. First it becomes whipped cream, then it turns grainy and dull, then all at once yellow clumps separate from a cloudy liquid. A jar and steady shaking works too; it simply takes longer.
Strain it. The liquid underneath is real buttermilk — keep it for pancakes and scones.
Work the clumps in iced water with the back of a spoon, pour the water off and repeat until it runs clear — three or four changes. Skip this and the butter turns bitter within three days.
Work in the salt now if you want it, wrap it tightly in paper and chill.

Why it works

Cream is fat droplets suspended in water, each wrapped in a thin phospholipid membrane that keeps it apart from its neighbours. Whipping tears those membranes; the exposed fat crystals stick together and past a certain point the whole system inverts — water inside fat, rather than fat inside water. That inversion is what butter is. Temperature decides it: below 10 °C the crystals are too hard to join, above 16 °C too soft, and between 10 and 14 °C it happens in about fifteen minutes. Washing is technique rather than hygiene: buttermilk trapped in the butter carries protein and lactose, and within days those turn rancid and bitter.

The rough sum

500 grams going in

1700 kcal in total

100% of the mass has figures behind it. This is the sum of what GOES IN rather than of what comes out. Wherever something evaporates, drains or ferments the two differ: a kilo of milk is 150 g of cheese.

Diets it qualifies for

Gluten-free Vegetarian

Storage & shelf life

How long it keeps

Fridge, unsalted and washed: 2 weeks
Fridge, salted at 2%: 1 month
Freezer: 6 months
Room temperature, in a covered butter dish: 1–2 days

Butter’s enemies are light and air, both of which oxidise the fatty acids. Left uncovered in the fridge it will also take on the smell of the onion beside it within a week, because fat dissolves aroma molecules. Wrapping it in paper or keeping it in a closed dish doubles its life on its own.

When to bin it Edges gone deep yellow-orange with a chalky, paint-like smell mean it has oxidised. The bitterness does not come back out; bin the whole piece rather than trimming it.

History

Where it comes from

Butter came into Turkish cooking through the churn. In nomadic life milk was agitated in a leather or hollowed-wood churn, the fat gathered up and the sour liquid left behind drunk as ayran — so ayran is the by-product of butter, not the other way round, and *yayık ayranı* is named for exactly that. For keeping, butter was melted and its milk solids removed to make sadeyağ; with the water and protein gone it survives months without refrigeration. In eastern Anatolia, rendering butter before winter was a calendar task, like laying out tarhana.

The knack

The fattier the cream the better the yield: 500 ml of 35% cream gives roughly 200 g of butter and 300 ml of buttermilk.
Drape a cloth over the bowl. At the moment it breaks, the liquid goes everywhere.
Unsalted butter freezes well; salted loses its flavour in the freezer sooner.

Milk and culture