Brew the base. Pull 1–2 shots of espresso, or make very strong coffee. Keep it hot.
Warm the milk. In a small saucepan over medium heat, warm the milk until steaming but not boiling.
Stir often to prevent scorching.
Whisk in the flavors. Add cocoa powder, chopped chocolate (if using), sugar, cinnamon, chili, vanilla, and a pinch of salt. Whisk until the chocolate melts and the mixture is smooth and glossy.
Taste and adjust. Add more sugar for sweetness, or another small pinch of chili if you want more heat. Keep it balanced.
Combine. Pour the hot espresso into a large mug.
Top with the spiced chocolate milk and stir gently.
Finish. Add whipped cream or foam if you like. Dust with a little cinnamon or cocoa for a café touch.