Brew two shots (about 2 oz total) of espresso using an espresso machine. If you don't have an espresso machine, brew 2 oz of very strong coffee and keep it hot.

Chocolate component

In a small heatproof cup, combine the unsweetened cocoa powder and granulated sugar. Add the 2 teaspoons of hot water and whisk to form a smooth paste with no lumps.

Stir in the tablespoon of finely chopped semisweet chocolate or chocolate chips into the cocoa paste. Microwave for 10–15 seconds or place the cup over a double boiler just until the chocolate melts. Stir until smooth and glossy.

Milk & foam

Pour 8 oz (about 1 cup) of whole milk into a frothing pitcher. Add 1 teaspoon vanilla extract and, if using, 1 teaspoon flavored syrup. Steam milk with a milk steamer/frother until it reaches about 150°F (65°C) and has velvety microfoam. If you don't have a steamer, heat milk on the stovetop until hot but not boiling (around 150°F), then froth vigorously with a handheld frother or whisk to create foam.

Give the espresso a quick stir, then pour the melted chocolate mixture into the hot espresso and whisk briefly to fully combine.

Slowly pour the steamed milk into the espresso-chocolate mixture, holding back foam with a spoon. Finish by spooning the remaining foam on top.

Finishing & optional

Top the mocha with 2 tablespoons of whipped cream if desired. Garnish with chocolate shavings or a light dusting of cocoa powder.

Serve immediately. Adjust sweetness to taste by adding more sugar or syrup before combining milk and espresso if needed.