For the Cake:
Preheat the Oven:
Preheat your oven to 350°F (175°C). Grease and flour a 9x13-inch baking pan or line it with parchment paper.
Prepare the Dry Ingredients:
In a bowl, whisk together the flour, baking powder, baking soda, and salt.
Cream Butter and Sugar:
In a separate large bowl, use a hand mixer or stand mixer to cream the butter and granulated sugar until light and fluffy.
Add Wet Ingredients:
Beat in the eggs one at a time, followed by the vanilla extract and sour cream.
Combine Dry Ingredients:
Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Fold in Peaches:
Gently fold in the diced peaches, ensuring they are evenly distributed.
Bake the Cake:
Pour the batter into the prepared pan and smooth the top. Bake for 35–40 minutes, or until a toothpick inserted into the center comes out clean. Let the cake cool completely.
For the Brown Sugar Frosting:
Cook the Base:
In a medium saucepan, melt the butter over medium heat. Add the brown sugar and stir until dissolved. Bring the mixture to a gentle boil and cook for 1–2 minutes.
Add Cream:
Remove from heat and stir in the heavy cream and vanilla extract. Let the mixture cool slightly.
Beat in Powdered Sugar:
Gradually beat in the powdered sugar until smooth and creamy. If the frosting is too thick, add a splash of cream to reach your desired consistency.
Frost the Cake:
Spread the frosting evenly over the cooled cake.