Pour popped popcorn onto a parchment lined baking sheet.
In the meantime, melt the butter in the skillet. Pour melted butter onto the baking sheet over the popped popcorn. Stir until evenly distributed.
Sprinkle salt and brown sugar over the popcorn. Bake for 10 minutes. (Baking isn't totally necessary, but it helps the brown sugar, butter mixture adhere to the popcorn better). Pour into a big bowl and enjoy!