For the pudding, I reduced the sugar to 1 cup and replaced the half-and-half with whole milk. It is still plenty rich.

For the chocolate pudding:
1 1/4 cup sugar
1/4 cup cornstarch
1/2 tsp salt
2 cups half-and-half
1 cup whole milk
6 ounces unsweetened chocolate, chopped
2 tsp vanilla extract

For the cake:
1 stick butter
1 1/2 cups all-purpose flour
2 tsp baking powder
1/2 tsp baking soda
1/2 tsp salt
3/4 cup dutch-processed cocoa powder
1 cup coffee
1 cup buttermilk
1 cup brown sugar
1 cup sugar
2 eggs
1 tsp vanilla extract