In an 8″ cast iron skillet, melt the butter over low-medium heat, then sprinkle the brown sugar evenly over top. Reduce heat to low and allow the sugar to melt into the butter. No need to stir, but don’t let the butter get too hot.
In a large bowl, combine cake mix, coconut flakes, shredded coconut, water, oil, applesauce, and eggs. Stir to combine.
Pour the batter into the skillet. The butter/brown sugar mixture will come up the sides and onto the top of the batter.
Bake 30-35 minutes or until a toothpick inserted in middle of cake comes out clean. Allow cake to cool. Serve warm with whipped cream. (You can also invert the cake after it’s been cooling for 10 minutes onto a large plate.)