Preheat your oven to 350°F (175°C). Gather all your ingredients and equipment.

Melt 4 tablespoons of salted butter in your pie plate for about 5 minutes. Sprinkle ¾ cup of brown sugar and 1 teaspoon of cinnamon over the butter, then arrange the sliced peaches on top.

In a medium mixing bowl, whisk together 1 ½ cups of flour, 1 teaspoon of baking powder, ½ teaspoon of baking soda, and ¼ teaspoon of salt.

Cream ½ cup of softened salted butter with 1 cup of granulated sugar until light and fluffy. Add in 1 large egg, ½ cup of sour cream, and 1 teaspoon of vanilla extract, mixing well.

Gradually add the dry mixture to the wet ingredients. Slowly pour in ½ cup of milk to create a smooth batter.

Pour the batter over the arranged peaches, smoothing the surface, and bake for 20 minutes, then cover with foil and bake for an additional 20-30 minutes.

Check for doneness by inserting a toothpick into the center. If it comes out clean or with a few crumbs, the cake is done.

Allow the cake to cool for about 5 minutes, then invert onto a serving platter and serve warm or at room temperature.