Preheat your oven to 350°F. In a large bowl, mix together the cake mix, eggs, vegetable oil, peach nectar, and a drop of food coloring (if using) until the batter is smooth and fully combined. Gently fold in the chopped peaches, then pour the batter into a 9×12-inch baking pan that has been lightly sprayed with non-stick cooking spray. Bake for approximately 28 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs—no wet batter.

To make the frosting, combine the butter, heavy cream, and brown sugar in a saucepan over medium heat. Bring the mixture to a boil, stirring constantly. Remove from heat and stir in the vanilla extract and sifted confectioners’ sugar. Whisk until the frosting is completely smooth and no lumps remain; return the pan to low heat briefly if needed to help dissolve the sugar.

Immediately pour the frosting over the warm cake, aiming to cover the entire surface in one go, as it sets quickly and won’t spread easily once it begins to firm up. Allow the frosting to harden at room temperature or chill the cake in the refrigerator before slicing and serving.