Homemade Recipe Boston Cream Cupcakes

Ingredients
🌾 1 2/3 cups all-purpose flour
🍬 1 cup granulated sugar
🥄 1/4 tsp baking soda
🥄 1 tsp baking powder
🧈 3/4 cup unsalted butter, at room temperature
🥚 3 large egg whites
🍦 2 tsp pure vanilla extract
🍶 1/2 cup sour cream
🥛 1/2 cup whole milk
🥛 1 cup heavy cream (for filling)
🥚 2 large egg yolks (for filling)
🍬 3 tbsp granulated sugar (for filling)
🥄 1 tbsp cornstarch (for filling)
🍦 1 tsp pure vanilla extract (for filling)
🥛 1/2 cup heavy cream (for ganache)
🍫 6 oz semi-sweet chocolate, chopped (for ganache)