Preheat oven:
Heat oven to 350°F (175°C).Melt butter, add sugar:
Place butter in a 12-cup muffin tin and melt it in the oven. Once melted, take the tin out and distribute brown sugar evenly over the butter.Place pineapple slices:
Put one pineapple slice into each cup. Optionally, place a maraschino cherry in the middle of each slice.Prepare cake batter:
Mix the cake batter following the instructions on the box.Fill muffin cups:
Divide the batter among the cups, filling each about two-thirds full.Bake cupcakes:
Bake for 20-25 minutes, until a toothpick inserted in the center emerges clean.Flip onto dish:
Let the cupcakes cool briefly. Carefully flip the tin onto a serving dish so the pineapple ends up on top.Serve warm:
Serve warm or at room temperature.