Boston Cream Cupcakes

Why I Love This Recipe
This is a great way to use up leftover egg yolks.
Ingredients You'll Need
2 eggs
6 Tbsp sugar
1/4 tsp salt
1/2 tsp vanilla extract
1/2 cup flour
---
Custard:
1/4 cup sugar
2 tsp cornstarch
1/2 cup milk
2 egg yolks, lightly beaten
1/2 tsp vanilla extract
3 Tbsp butter, softened
---
Frosting:
1 1/2 cups sugar
1/4 cup cocoa
2 Tbsp butter
1/2 tsp vanilla
2 tbsp milk
Directions
Preheat oven to 350F. Line a cupcake pan with liners. In a small bowl, beat eggs until light and fluffy. Gradually add sugar and salt, beating until thick and lemon-colored, about 5 minutes. Stir in vanilla. Fold in flour, 2 Tbsp at a time. Spoon into a cupcake pan. Bake 15-20 minutes or until cakes springs back when touched. Cool for 10 minutes before removing from pans to cool completely.
Custard: In a small pan, combine sugar and cornstarch. Stir in milk until smooth. Cook and stir over medium heat until thickened and bubbly. Reduce heat; cook and stir 2 minutes longer. Remove from heat. Stir a small amount into egg yolks before adding them to the pan (Adding a little bit of heat first will keep it from turning into scrambled eggs). Bring to a gentle boil; cook and stir 2 minutes longer. Remove from heat and let cool to room temperature without stirring. Once cool, cream butter and gradually beat in custard.
Frosting: Beat frosting ingredients until mixed. Add more milk if necessary.
To assemble: Cut a hole out of each cupcake middle and reserve crumbs. The batter may be sticky. Spoon custard into each center. Pipe frosting on top and garnish with reserved crumbs.