Measure 4 cups whole milk, 4 tablespoons unsweetened cocoa powder, 4 tablespoons granulated sugar, and have 2 ounces finely chopped bittersweet or semisweet chocolate ready.

Make cocoa slurry

In a small bowl, whisk together the cocoa powder and 2 tablespoons of the milk (taken from the 4 cups) until smooth and lump-free to form a slurry. This prevents clumping when added to hot milk.

Heat milk

Pour the remaining milk into a medium saucepan. Add the pinch of salt. Warm over medium heat until steam appears at the edges and small bubbles form (do not boil), about 4–6 minutes, stirring occasionally so milk does not scorch.

Combine slurry and sugar

Whisk the cocoa slurry and granulated sugar into the warm milk. Continue to heat, whisking constantly, until the mixture is hot and begins to steam, about 1–2 minutes more.

Add chopped chocolate

Reduce heat to low and add the chopped chocolate. Whisk continuously until the chocolate is fully melted and the mixture is smooth and glossy, about 1–2 minutes.

Finish

Remove pan from heat and stir in 1 teaspoon vanilla extract. Taste and adjust sweetness if desired by adding up to 1 tablespoon more sugar. Keep warm on lowest heat setting if serving immediately.

Optional Toppings & Add-ins

Make a mocha (optional)

If adding a shot of espresso, prepare one shot and pour it into each serving cup before ladling the hot chocolate on top. Stir to combine.

Spice it up (optional)

For a spiced version, add a pinch (about 1/8 tsp) of cayenne pepper to the saucepan with the cocoa slurry, or sprinkle 1/4 to 1/2 tsp ground cinnamon into the mixture while heating. Stir well.

Serve with toppings

Ladle hot chocolate into 4 warmed mugs. Top each with a generous dollop of whipped cream and a handful of mini marshmallows if desired. Sprinkle dark chocolate shavings and a light dusting of ground cinnamon over the top.

Keep warm and reheat

If holding for a short period, keep the saucepan on the lowest heat and whisk occasionally. To reheat, warm gently over low heat, whisking until smooth; avoid boiling to prevent milk from scalding.