Preheat your oven to 350°F (175°C) and grease a 13x9-inch baking dish.

Blanch fresh peaches for about 30 seconds, cool in ice bath, and chop them.

In a large mixing bowl, combine cake mix, melted butter, peach nectar, vanilla extract, and eggs. Mix until creamy.

Gently fold in the chopped peaches into the batter.

Pour batter into prepared baking dish and bake for 25-30 minutes. Check for doneness with a toothpick.

In a saucepan, combine brown sugar, butter, and cream. Bring to boil while whisking constantly for 30-45 seconds.

Remove from heat, whisk in vanilla, and gradually add powdered sugar to achieve smooth icing.

Pour warm icing over hot cake immediately and spread evenly with a spatula.

Allow the cake to cool in the pan for about 20 minutes before slicing.