Preheat oven to 350.
Pour melted butter into the bottom or a 13x9-inch pan coated with cooking spray. Roughly chop cranberries in a food processor; pour into a medium bowl. Add both sugars to cranberries and stir to combine. Pour cranberry mixture evenly over melted butter.
Follow the directions on the box to prepare the yellow cake mix and pour it over everything. Bake for 40-50 minutes, or until a toothpick inserted in the center comes out clean.
Let cool for 10 minutes. Then, with a knife, loosen the cake from edges of the pan and turn the pan over on a plate. Serve with whipped cream or ice cream.