get your smoker setup to cook at 350 degrees
Pour three tablespoons of melted butter into the bottom of your 12" skillet
sprinkle 1 cup of brown sugar over top of the butter. Make sure the butter and brown sugar mixture covers the entire bottom of your skillet
Place pineapple slices on top of the brown sugar mixture, and then place one cherry inside each of the pineapple slices. Don't discard the pineapple juice!
Prepare the cake mix per the instructions on the side of the box, but replace the water with the reserved pineapple juice.
Thoroughly mix the batter, and then pour it over the pineapples and cherries. Put the skillet in your hot smoker, and let it cook for about 40 minutes.
The cake is done when a toothpick can be inserted in the center and pulls out clean.
When the cake is done remove it from the smoker and let it cool for ten minutes.
Run a spatula around the outer edge of the cake, and then place a large cutting board on top of the skillet. Carefully flip the skillet and cutting board (to make the skillet upside down!) Tap on the top of the skillet a few times to make sure the cake has come out, and then remove the skillet.