1/4 cup of good quality unsweetened cacao powder (such as Pernigotti)
1/4 cup sugar
2 tablespoons Potato starch (corn starch in the US)
3 1/2 cups of milk
In a small saucepan, combine all the ingredients. Whisk over medium heat until smooth. Continue whisking until the mixture is warm and has thickened (about 5 minutes). Serve with a dollop of whip cream if desired.