Wash the peaches carefully and pat them dry. Peel them if desired, then remove the pits. Slice the peaches evenly and place them in a bowl with lemon juice.

Preheat the oven to 350°F. Grease a 9-inch round cake pan thoroughly. Line the bottom with parchment paper to make removing the finished cake easier.

Add flour, baking powder, baking soda, salt, and cinnamon to a medium bowl. Whisk gently until everything is evenly combined. Set the bowl aside while preparing the wet ingredients.

Place softened butter and granulated sugar into a large bowl. Beat them until light and creamy. This usually takes two to three minutes with an electric mixer.

Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract. The mixture should look smooth and creamy before adding the remaining ingredients.

Add sour cream to the wet mixture. Mix gently until smooth. Sour cream helps create a soft, tender cake texture while adding a pleasant richness to every bite.

Gradually add the dry ingredients to the wet mixture. Stir gently with a spatula until just combined. Do not overmix because this can make the cake dense.

Fold half of the sliced peaches gently into the batter. Spread the batter evenly into the prepared pan. Arrange the remaining peach slices over the surface.

Sprinkle brown sugar lightly over the peaches. This creates a lightly caramelized top while baking. Make sure the sugar is distributed evenly across the fruit.

Place the pan in the preheated oven. Bake for about 40 to 45 minutes. The cake is ready when the center feels set and a toothpick comes out mostly clean.

Let the cake cool in the pan for about 15 minutes. Transfer it carefully to a wire rack. Dust with powdered sugar before serving warm or completely cooled.