Cold foam is milk aerated cold — no steam wand, no heat — until it holds like a loose meringue. Poured over cold brew it sits as a distinct layer and works its way down the glass as you drink, so the first mouthful is sweet and milky and the last is black coffee. It takes thirty seconds with a hand frother.
What you need
- 150ml of cold brew concentrate, diluted to taste
- 60ml of cold milk
- 5g of muscovado, or 5ml of vanilla syrup
- A hand frother, or a jar with a lid
- A tall glass of ice
The method
- Fill the glass with ice and pour the cold brew over it, leaving 3cm at the top.
- Put the cold milk and the sweetener into a narrow jug or a jar.
- Froth for twenty to thirty seconds, keeping the whisk just below the surface, until the volume roughly doubles and the milk falls slowly off a spoon.
- Spoon or pour it gently over the coffee so it holds as a layer.
- Serve it unstirred.
The concentrate
This assumes a concentrate rather than ready-to-drink coffee, diluted one to one. Our cold brew guide covers making it: 100g of coarse coffee per litre, sixteen hours, strained twice.
Getting the foam to hold
Everything must be cold, the jug included. Barista oat holds best; a thin milk will foam and then collapse inside a minute. If you are using a jar, fill it no more than a third and shake hard for thirty seconds — it is louder and it works just as well.
Sweeten the foam, not the coffee
Sugar in the foam is what lets this read as a treat while the coffee underneath stays dry and bitter. Sweeten the cold brew as well and the whole glass goes flat and one-note.
Which coffee
Cold brew already softens acidity, and under sweet foam a subtle coffee will disappear entirely. Darago is the sturdy choice — caramel and toasted almond that hold up against the foam, and a milk chocolate finish that keeps the bottom of the glass interesting.