Using a stand mixer with the paddle attachment, cream the butter and sugar until light and fluffy.
1/2 cup unsalted butter, 1 cup sugar
Mix in the egg, then sour cream and vanilla until smooth.
1 large egg, 1 cup sour cream, 2 tsp vanilla extract
Blend in half of the flour mixture until somewhat incorporated.
Add in the rest of the flour mixture, blend and scrap down the sides as needed until just combined. Batter will be super thick.
Spoon onto prepared baking pan and spread out as evenly as possible. Set aside.
To prepare the topping
Clean the mixing bowl and switch to the whisk attachment.
Mix the cream cheese and sugar until blended.
8 oz (250 g) cream cheese, 1/2 cup granulated sugar
Whisk in the egg white and vanilla until smooth.
1 tsp vanilla extract, 1 large egg white
Spread over cake batter and place sliced peaches on top.
3 peaches
Bake for 30 minutes or until edges are nice and brown. Let cool to room temperature and serve.
Notes
Cake can be stored in the refrigerator for 3-4 days. Bring to room temperature before serving.You can also substitute the peaches for strawberries if you prefer strawberries and cream. Enjoy!