Preheat oven to 350 deg. lightly grease a 9 X 13 baking dish with butter or non-stick spray

Beat together cake mix, jello, eggs, oil and vanilla in a large bowl or mixer until just incorporated, then fold in the chopped peaches

Pour batter into greased baking dish, then place in oven and bake for 40 t0 45 minutes or until toothpick inserted in center comes out clean

Remove cake from oven and let cool completely

While cake is cooking, combine brown sugar, heavy cream and butter in a large sauce pan over medium heat

Bring mixture to a boil and cook for an additional 1 minute, then remove mixture from the heat stir in the vanilla extract

Set up ice bath with a large bowl full of ice water (If desired). Carefully place frosting pan into the ice bath and use a mixer to being careful not to get any water into the frosting mix. Beat until mixture cools, thickens fluffy and airy. About 4 to 5 minutes

Spread frosting over cooled cake, then slice into squares and enjoy