2 1/2 cups (354g) all-purpose flour
1 tsp baking powder
1/2 tsp salt
10 Tbsp (5 oz) unsalted butter, softened slightly*
1 cup (215g) granulated sugar
Seeds of 1 small vanilla bean
1 large egg
1 large egg white
3 Tbsp sour cream
1/2 tsp vanilla extract

Frosting
1/2 cup (4 oz) butter (I like to use 1/4 cup salted and 1/4 cup unsalted)
Seeds of 1 small vanilla bean
1/2 tsp vanilla extract
2 cups (240g) powdered sugar
2 Tbsp half and half