INGREDIENTS
1 cup
sugar, divided
1/2 cup
cocoa powder, divided
1 cup
all-purpose flour
2 tsp
baking powder
1/4 tsp
salt
1/2 cup
milk
4 tbsp
butter, melted
1
large egg yolk
1 tsp
vanilla extract
1/2 cup
semisweet chocolate chips
1 cup
boiling water
Vanilla ice cream, for topping