Prep the pan and oven: Heat the oven to 350°F (175°C). Grease a 9-inch round cake pan or a 10-inch oven-safe skillet. Line the bottom with parchment for easy release.

Make the peach topping: Melt 1/2 cup butter. Pour it into the pan and sprinkle the brown sugar evenly over the butter. Add a squeeze of lemon juice. Arrange peach slices in concentric circles over the sugar layer.

Whisk dry ingredients: In a bowl, whisk flour, baking powder, salt, and optional cinnamon or cardamom.

Cream the butter and sugar: In a separate bowl, beat 1/2 cup softened butter with granulated sugar until light and fluffy, about 2–3 minutes.

Add eggs and vanilla: Beat in eggs one at a time, then mix in vanilla until smooth.

Finish the batter: Mix in half the dry ingredients, then the sour cream and milk, then the remaining dry ingredients. Stir just until combined. Do not overmix.

Assemble: Gently spread the batter over the peaches, smoothing the top. The pan will be fairly full.

Bake: Bake 40–50 minutes, until the center springs back and a toothpick comes out clean. If the top browns too quickly, tent loosely with foil.

Cool and flip: Let the cake rest 10–15 minutes. Run a knife around the edge, place a serving plate over the pan, and carefully invert. Lift off the pan and peel away the parchment.

Serve: Spoon any caramel left in the pan back over the cake. Serve warm with vanilla ice cream or whipped cream.