Ingredients:
For the Cupcakes:
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
For the Filling:
1 cup heavy cream
2 large egg yolks
3 tbsp granulated sugar
1 tbsp cornstarch
1 tsp pure vanilla extract
For the Chocolate Ganache:
1/2 cup heavy cream
6 oz semi-sweet chocolate, chopped (for a smoother ganache)
Directions:
1. Cupcakes: Preheat your oven to 350°F (175°C). In a large bowl, whisk together the flour, sugar, baking soda, and baking powder. Add the softened butter, egg whites, vanilla extract, sour cream, and milk; beat until the batter is smooth and creamy. Fill cupcake liners about 2/3 full and bake for 18-20 minutes or until a toothpick inserted comes out clean. Allow to cool completely on a wire rack.
2. Filling: In a medium saucepan, heat the heavy cream until it starts to simmer. In a separate bowl, whisk together the egg yolks, sugar, and cornstarch until smooth. Gradually temper in the hot cream by slowly whisking it into the egg yolk mixture to avoid cooking the eggs. Return the mixture to the saucepan and heat, constantly stirring, until the mixture thickens to a custard-like consistency. Remove from heat and stir in the vanilla extract. Transfer to a bowl, cover with plastic wrap directly on the surface to prevent a skin from forming, and chill in the refrigerator until cold.