Preheat the oven to 350 degrees F. Line a large rimmed baking sheet with parchment paper.
In a microwave-safe bowl, melt the butter. Stir in the brown sugar and cinnamon.
Quickly dunk each bun in the butter mixture. Wipe the excess off into the bowl and place them on the baking sheet. If you run low on butter mixture, roll the last few buns around in the pan drippings.
Bake the buns for 8 minutes. Leave the buns in the oven. Turn the oven to broil, and broil for 1-2 minutes. Just long enough for the tops to get a little crusty. (Watch closely so they don't burn.) Serve warm.