Begin by melting 1/4 cup of salted butter in a 9-inch pie plate. Sprinkle 1/2 cup of brown sugar and 1/2 teaspoon of cinnamon over the butter, then arrange 2 cups of peach slices on top.

Preheat your oven to 350°F (175°C).

In a mixing bowl, combine 1 1/2 cups of all-purpose flour, 1 teaspoon of baking powder, 1/2 teaspoon of baking soda, and 1/2 teaspoon of salt. Whisk until fully combined.

In a stand mixer, cream 1/4 cup of salted butter and 3/4 cup of sugar together until light and fluffy, about 3 to 5 minutes.

Add in 1 egg, 1/2 cup of sour cream, and 1 teaspoon of vanilla extract. Beat until incorporated. Gradually add the dry mixture and mix until just combined.

Slowly pour in 1/3 cup of milk and mix until well combined.

Pour the batter over the arranged peach slices in the pie plate, spreading it evenly. Bake for 20 minutes, then tent with foil and continue to bake for an additional 20-30 minutes until a toothpick comes out clean.

Allow the cake to cool in the pan for about 5 minutes, then run a knife around the edges and invert onto a serving platter.