straight from the Pioneer woman: I make this a lot!
1 cup unsweetened cocoa powder
1 cup sugar
1 cup heavy cream
1 stick(1/2) cup salted butter, cut in pieces
3 teaspoons vanilla extract
In a medium sauce pan, gently whisk together the cocoa and sugar. Whisk in the cream and turn the heat to medium, whisk it as it warms up. When the mixture starts to heat up add the butter when mixture is hot add vanilla and stir to combine. Let mixture cool, add to a jar and put in fridge. To use, take out amount needed, heat in microwave 20 seconds til warm.