For the cake:
1/2 cup unsalted butter, softened at room temperature for 1 hour
1 1/2 cups sugar
3 large eggs
2 1/4 cups all-purpose flour
1 teaspoon salt
3 1/2 teaspoons baking powder
1 1/4 cups whole milk
2 teaspoons pure vanilla extract
For the cream:
2 cups heavy cream
1/2 cup sour cream
1/4 cup powdered sugar
For the fruit:
2 nectarines or peaches, sliced
1 apricot, sliced
1/2 cup chopped strawberries
1/2 cup blackberries
Preheat the oven to 350°F. Prepare a 9x13-inch pan by greasing it thoroughly with baking spray.
Use a hand mixer or stand mixer to beat the softened butter and sugar together until fluffy and light, then add the eggs and beat until fully incorporated and creamy. Beat in the flour, salt, baking powder, and finally the milk and vanilla. Beat the cake batter on low for 30 seconds, then medium-high for 3 minutes.
Immediately pour into the prepared pan and bake for 40 to 45 minutes, or until the tops spring back slightly when pressed and a toothpick inserted near the center comes out clean.
Cool the cake completely, for at least an hour.
Beat the cream, sour cream, powdered sugar, and salt together until soft peaks form. Spread over the cooled cake, then top with the sliced or chopped fruit.
Refrigerate until serving, and refrigerate any leftovers for up to 5 days.