Pull two shots of espresso (about 60 ml total). If you don't have an espresso machine, brew 60 ml of very strong coffee or use 2 shots' worth of concentrated instant espresso mixed with 60 ml hot water. Keep the espresso hot and set aside.

Caramel Sauce (if using homemade)

Make quick caramel (optional)

In a small saucepan over medium heat, combine 1 tablespoon brown sugar and 1 teaspoon water. Stir until sugar dissolves, then let it bubble without stirring for 1–2 minutes until it turns a deep amber. Remove from heat and carefully stir in a pinch of salt and 1 tablespoon butter or a splash (5 ml) cream if desired to smooth. Let cool slightly. Alternatively, use 2 tablespoons store-bought caramel sauce and skip this step.

Milk

Heat and froth milk

Pour 1 cup whole milk into a small saucepan and heat over medium-low until it reaches about 60–65°C (140–150°F) — steaming but not boiling and small bubbles form at the edges. If using a milk frother or steam wand, steam the milk until velvety microfoam forms. If you don't have a frother, whisk vigorously or use a handheld frother for 20–30 seconds to create foam. Reserve ~1/4 cup of foamed milk for the top if possible.

Assemble

Combine espresso and caramel

In a 12–16 oz (350–475 ml) mug, add 2 tablespoons caramel sauce and 1/4 teaspoon vanilla extract. Pour the hot espresso over the caramel and stir vigorously until the caramel is fully dissolved and the mixture is homogenous.

Add milk

Slowly pour the steamed milk into the mug while holding back the foam with a spoon. Once most of the milk is in, spoon the reserved foam on top to create a creamy head.

Finish

Taste and add a pinch of salt if desired to enhance caramel flavor. Top with an optional 2 tablespoons whipped cream and drizzle 1 tablespoon extra caramel sauce over the foam or whipped cream. Serve immediately.