Drain both fruit cans & reserve juices. Cut up peach slices into smaller chunks. Lightly spray a 9x13 baking dish. Pour fruit inside.
Top with dry cake mix, crumbling any large chunks as you go. Top cake mix with 4 Tbsp of butter cut up into pieces.
Pour reserved juices evenly over the top of the cake & butter. Cook at 350˚F for 30-40 minutes or until bubbly & cake is cooked (gooey, but not runny; closer to 40 minutes.) Serve with ice cream or whipped cream.