Preheat oven to 350Ëš F. Grease a 9" round cake pan (with at least a 2" height). Line bottom with a sheet of parchment paper.
Add melted butter onto the bottom of cake pan. Sprinkle with ½ cup of brown sugar. Start in the middle and place peach slices barely overlapping each other on concentric circles around the pan. Set aside.
In a large bowl, whisk together flour, baking powder, nutmeg, and cinnamon. In a smaller bowl, whisk eggs, sugar, and sour cream. Add sugar mixture to flour mixture, stirring with a spoon until fully combined.
Pour batter gently on top of peaches, making sure that batter is spread evenly. Bake for 30-35 minutes or until a toothpick inserted into the middle comes out clean. Let cool on a rack for 10 minutes before flipping onto a serving platter.
Notes
This recipe is best eaten the same day it's eaten, but you can definitely enjoy it the next day.  Store at room temperature. The cake will be good for 2-3 days if covered tightly in plastic wrap.Â