Preheat oven to 350°. Get out a 12-inch cast iron skillet.
When the cake is done, remove from oven and let sit for a couple of minutes. Take a large serving platter and place it face-down on the hot skillet. With one hand held flat on the bottom of the platter and the other holding the handle of the skillet (using a hot pad! The skillet will be hot), flip the cake over. Once the platter is firmly on the counter, use both hands to gently lift the skillet away.
You can find Challenge Butter here. (Clickable Link)