1 cup whole milk
1 1/2 teaspoons brown sugar, or to taste
2 ounces dark chocolate (such as Moser Roth® 85% Dark Chocolate), or to taste
1 tablespoon heavy whipping cream, or more to taste
1 pinch ground cinnamon, or more to taste
Heat milk in a saucepan over medium heat until just before boiling, 3 to 4 minutes. Add brown sugar and stir until dissolved, about 1 minute. Stir dark chocolate into milk until melted, 2 to 3 minutes. Remove saucepan from heat and stir cream and cinnamon into milk mixture.