Boston Cream Pie (Rich's Birthday Cake)

Since 1967, Rich has had a Boston Cream Pie for his birthday. Some years he had a store cake, but the best has always been homemade. 

After many years of trying different recipes, this has become the one that is the best! Due to the extensive preparation time, he is limited to one per year, which works well since he only celebrates one birthday per year. 
Picture
Ingredients: Cream Filling

2 large egg yolks
1 1/2 cups whole milk (can use half and half)
1/3 cup granulated sugar
2 Tbs corn starch
1/8 tsp salt
2 tsp vanilla 

Ingredients: Cake

1 Duncan Hines Classic Butter Golden cake mix
Parchment paper

Ingredients: Chocolate Icing

3 Tbs butter
3 oz. unsweetened baking chocolate (squares work best)
3 - 4 Tbs water
1 cup powdered sugar
3/4 tsp vanilla

NOTE: Carol adds 1 oz. chocolate and 1/4 cup powdered sugar to make enough frosting to cover sides of cake


Preparation: Filling
  1. In a small bowl beat the egg yolks until mixed, stir in milk and set aside
  2. Stir in sugar, corn starch and salt into a two quart sauce pan
  3. Gradually stir in egg mixture into sauce pan with the sugar mixture
  4. Cook over medium heat, stirring constantly, until mixture thickens and comes to a boil
  5. Boil and stir 1 minute and remove from heat
  6. Stir in vanilla
  7. Place mixture into a bowl and press plastic wrap on the surface of the filling
  8. Refrigerate at least 2 hours, but no longer than 24 hours

Preparation: Cake
  1. Prepare cake according to directions on the box - NOTE: Divide the cake batter evenly between two 8" cake pans, creating two separate cakes from the one box
  2. For best results, line the bottom of the cake pans with Parchment paper cut to fit inside
  3. Cool the cakes 
  4. Once cakes are cooled, release from the pans and place one cake upside down on a plate
  5. Spread Filling over top of this cake
  6. Place second cake on top of the filling

Preparation: Chocolate Icing
  1. Microwave water for 30 seconds until hot
  2. In a one quart sauce pan melt the butter and chocolate over low heat - stirring occasionally
  3. Remove chocolate mixture from heat, stir in powered sugar and vanilla
  4. Stir in 3 Tbs hot water, adding additional hot water by 1 tsp at a time, until icing is smooth and thin enough to spread
  5. Spread icing over cake top, allowing some to drizzle on sides
  6. Refrigerate uncovered until ready to serve