1. Preheat the oven to 350°F (175°C) and grease and line a 9-inch springform pan with parchment paper.

2. In a bowl beat softened butter and granulated sugar until light and pale.

3. Add eggs one at a time, then stir in vanilla extract and sourdough starter until combined.

4. Whisk flour, baking powder, baking soda, and salt in a separate bowl.

5. Add dry ingredients to the wet mixture alternately with buttermilk, mixing until just smooth.

6. Toss sliced peaches with brown sugar and cinnamon until evenly coated.

7. Spread two thirds of the batter into the prepared pan.

8. Arrange the peach slices over the batter in an even layer.

9. Beat together softened cream cheese, sugar, egg yolk, and vanilla for the cream layer and dollop over the peaches.

10. Spoon the remaining batter over the cream layer, allowing bits of peach and cream to show through.

11. Bake for 45 to 55 minutes or until a toothpick inserted into the center comes out mostly clean.

12. Let the cake cool in the pan for 10 minutes, then run a knife around the edges and release the springform collar. Transfer the cake with parchment to a wire rack to cool completely.

13. Whisk powdered sugar, heavy cream, and vanilla extract until smooth and pourable.

14. Drizzle the glaze over the cooled cake and let it set before slicing.