Ingredients 

2 1/4 cups all-purpose flour, 1 1/2 teaspoons baking powder, 1/2 teaspoon salt, 1 cup (2 sticks) unsalted butter,  4 large eggs,

2 cups granulated sugar, 1 cup sour cream, 1 1/2 teaspoons pure vanilla extractm, 1 cup whole milk, 2 large eggsm 1/2 cup granulated sugar,

1/4 cup all-purpose flour, 1/4 cup unsalted butter, 1 cup heavy creamm 1/4 cup powdered sugarm 1 teaspoon pure vanilla extract

Instructions 

Preheat oven to 350 degrees F (175 degrees C). Grease and flour two 9-inch round cake pans. In a medium bowl, whisk together the flour, baking powder, and salt..

In a large bowl, cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time, then stir in the sour cream and vanilla extract.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix. Divide the batter evenly between the prepared cake pans.

Bake for 25-30 minutes, Let the cakes cool in the pans for 10 minutes before inverting them onto wire racks to cool completely.

To make the custard, whisk together the milk, eggs, sugar, and flour in a medium saucepan. Cook over medium heat, whisking constantly,

Remove from the heat and stir in the butter until melted. Pour the custard over one of the cooled cake layers. Top with the other cake layer.

To make the whipped cream, beat the heavy cream, powdered sugar, and vanilla extract together until stiff peaks form.

Frost the top and sides of the cake with the whipped cream. Refrigerate the cake for at least 30 minutes before serving.