Preheat the oven to 350°F.

Butter and flour the sides and bottom of a springform pan. Line the bottom with a 9-inch round piece of parchment paper.

In a small bowl, whisk together the granulated sugar and ground cinnamon for the cinnamon sugar topping and set aside.

In a medium-sized bowl, whisk together the flour, baking powder, baking soda, and kosher salt for 30 seconds.

Crack the eggs into a small bowl and cut the peaches into 1/2-inch wide wedges, cutting larger pieces in half.

In the bowl of a stand mixer, combine the unsalted butter, granulated sugar, ground cinnamon, ground nutmeg, and vanilla extract. Mix on low for about 20 seconds, then increase to medium and beat until creamy and slightly lighter in color, about 2 minutes and 30 seconds. Scrape down the bowl and the paddle attachment.

Add the eggs one at a time, beating after each addition until fully incorporated.

Add half of the flour mixture and mix on low until incorporated. There may be some flour on the sides of the bowl. Add the sour cream and mix on medium until incorporated. Add the remaining flour mixture and mix on low until incorporated. Scrape the sides and bottom of the bowl.

Pour half the batter into the prepared springform pan and smooth into an even layer. Spread half of the peaches across the batter. Sprinkle half of the cinnamon sugar mixture over the peaches and cake batter. Add the remaining batter and spread it evenly on top. Arrange the remaining peaches on top and sprinkle with the remaining cinnamon sugar mixture.

Bake for 55-60 minutes until the top is golden brown and an inserted cake tester comes out clean with a few crumbs. The internal temperature should be 200-205°F.

Remove the cake from the oven and set the pan on a wire rack. Run an offset spatula around the edges to loosen the cake. Let it cool in the pan for 15 minutes. Remove the ring of the springform pan and let the cake cool completely before slicing and serving.