01 - Preheat the oven to 350°F. Grease and flour a 9-inch round cake pan or springform pan.
02 - In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.
03 - In a large bowl, beat together the melted butter and sugar until smooth. Add the eggs, one at a time, mixing well after each. Stir in the sour cream and vanilla extract.
04 - Gradually fold the dry ingredients into the wet ingredients until just combined. Do not overmix.
05 - Gently fold in two-thirds of the peach slices.
06 - Pour the batter into the prepared pan and smooth the top. Arrange the remaining peach slices on top of the batter in a circular pattern.
07 - In a small bowl, mix the sugar and cinnamon for the topping. Sprinkle evenly over the peaches.
08 - Bake for 38–42 minutes, or until a toothpick inserted into the center comes out clean and the top is golden brown.
09 - Let the cake cool in the pan for 10 minutes, then run a knife around the edge and release the cake onto a wire rack to cool completely. Serve slightly warm or at room temperature, plain or with a dollop of whipped cream.