Pastry Cream

1. In a medium sauce pan, stir together the milk and 1/4 cup sugar. Bring to a simmer on the stovetop over medium heat. In a separate mixing bowl, whisk together egg, egg yolks, cornstarch, and 1/3 cup sugar.
2. Once the milk has reached a simmer, carefully pour half of the hot milk in a steady stream into the egg mixture, whisking constantly to avoid curdling the eggs. Immediately whisk the egg mixture back into the saucepan.
3. Return to stovetop and continuing to cook over medium heat while whisk constantly until mixture thickens.
4. Remove from heat once thickened and stir in butter and vanilla until melted. Pour into a clean mixing bowl and press a sheet of saran wrap directly on top of the surface of the pastry cream to prevent a skin from developing. Cool completely in the refrigerator for at least 4 hours.

Cake

1. Preheat oven to 350F. Grease two 9″ pans and line the bottom with parchment paper.
2. In a large mixing bowl, use a hand mixer to cream the butter, vegetable oil, and sugar together until light and fluffy. Add in buttermilk, eggs, and vanilla and beat until combined. The mixture will look curdled, but that’s okay. It will come together when you add in the dry ingredients.
3. Add in flour, baking powder, and salt, and mix until just combined. Divide the batter among the two prepared baking pans.
4. Bake for 25 – 30 minutes or until a toothpick inserted into the center comes out clean.
5. Let cool completely before assembling.