Preheat the oven to 350 degrees F.

Grease a 9x13 inch cake pan.

In a large bowl or stand mixer, beat together the cake mix, 2 boxes of peach Jell-O, 4 eggs, and the cup of oil.

Open the bag of frozen sliced peaches. Cut each slice in half so they are a little more bite size.

Use a sturdy wooden spoon to fold the peaches into the cake batter.

Pour the batter into the greased cake pan.

Bake at 350 for about 40-45 minutes. Check the center of the cake with a toothpick; if it comes out without batter it is done. (very moist crumbs are ok.) The edges will be quite brown.

Let the cake cool completely on a wire rack.

While the cake cools, make the brown sugar frosting. In a 2 quart pot, add butter, brown sugar, and heavy cream.

Stir together over medium high heat until it reaches a boil (bubbles all the way across the top). Set a timer for 1 minute and stir frequently.

Remove from heat. Stir in the vanilla.

Prepare an ice bath. Set the pot of frosting in the ice bath (don't get water in the frosting!!) Let the frosting cool in the ice bath, scraping sides occasionally, until the frosting is room temperature and much thicker. See photos.

Use a hand mixer to beat the frosting for about 3-5 minutes, until it is thicker but still pourable.

Spread the frosting over the cooled cake.

This keeps on the counter for a day or two, but after that I would put it in the fridge. Good luck keeping it around that long!