Frothy Hot Chocolate

4 1/2 cups low-fat milk
2 tablespoons unsweetened cocoa powder
1/3 cup sugar
1/3 cup coffee liqueur(optional)
1 1/2 teaspoons ground cinnamon
1 1/2 teaspoons vanilla extract

Whisk together 1/2 cup milk, sugar, coffee liqueur (if using), cocoa, vanilla and cinnamon in a small bowl until a smooth paste forms.

Heat the remaining 4 cups milk in a medium saucepan until steaming. Remove from heat and whisk vigorously.

Whisk the cocoa mixture into the milk and pour into mugs.