Preheat your oven to 350°F (175°C). In a large mixing bowl, combine the yellow cake mix, eggs, vegetable oil, and peach nectar. Blend until smooth for about 2 minutes.

Gently fold the chopped fresh peaches into your cake batter using a spatula, then pour the batter into a greased 9x12 baking pan.

Place the baking pan in the oven and bake for approximately 28 minutes. Ensure a toothpick comes out with a few moist crumbs.

In a medium saucepan over medium heat, combine the unsalted butter, heavy cream, and brown sugar. Bring to a boil while stirring for about 3-4 minutes until thickened.

Remove the caramel mixture from heat, stir in the vanilla extract, and whisk in the powdered sugar until smooth.

Pour the warm caramel frosting over the top of the cake and spread it evenly.

Allow the cake to cool at room temperature for about 30 minutes before slicing.