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