Warm your cup: Fill your mug with hot water while you prepare the coffee.
This helps your cappuccino stay hot and keeps the foam stable.
Brew the espresso: Pull 1–2 shots of espresso. If you don’t have an espresso machine, brew 1/3 cup of very strong coffee using an Aeropress, Moka pot, or a concentrated pour-over.
Mix the flavor base: In a small bowl, combine the chestnut puree, vanilla extract, and sweetener. If the puree is very thick, add a teaspoon or two of hot water to make it glossy and spoonable.
Heat the milk: Warm milk to about 150–155°F (65–68°C).
It should be hot but not boiling. On the stove, heat gently and keep an eye on it; in the microwave, short bursts work best.
Froth the milk: Use a steam wand, handheld frother, French press, or whisk. Aim for a fine, velvety microfoam.
A French press makes this easy—pump 15–20 times until the milk doubles in volume.
Combine espresso and chestnut base: Pour the espresso into your warmed mug (discard the hot water first). Stir in the chestnut-vanilla mixture until smooth.
Add the milk: Pour in the hot milk, holding back the foam with a spoon. Then spoon the foam on top.
A classic cappuccino has about equal parts espresso, steamed milk, and foam.
Finish and serve: Dust with a pinch of cinnamon or nutmeg if you like. Taste and adjust sweetness while it’s still hot.