Preheat the oven to 350°F. In a large bowl, blend together the cake mix, eggs, oil, nectar, and food coloring, if using, until well combined. Gently fold in the chopped peaches. Turn the batter into a lightly sprayed 9×12-inch baking pan. Bake for about 28 minutes, or until a toothpick inserted into the center comes out clean or with moist crumbs (but no wet batter).

While the cake bakes, prepare the frosting. In a medium saucepan, combine the butter, cream, and brown sugar. Bring to a boil over medium heat, stirring constantly. Remove from heat, add the vanilla extract and sifted confectioner’s sugar, and whisk until smooth. If needed, briefly return the saucepan to low heat to help dissolve any lumps.

Once the cake is done and slightly cooled, pour the frosting evenly over the surface of the cake. Try to coat the cake in one pass—this frosting sets up quickly and can crack if spread after it starts to firm. Let the frosting harden at room temperature or chill it in the refrigerator before slicing and serving.