Preheat oven to 350°F and spray 24 muffin cups with cooking spray.
Line a surface with parchment paper.
Add 1 tsp melted butter to each muffin cup.
Add 1 tbsp brown sugar to each cup.
Place a cherry in the center of each cup.
Top each with a heaping tbsp crushed pineapple.
Make cake batter per box instructions, using pineapple juice instead of water.
Pour batter into prepared muffin cups, filling almost to the top.
Bake for 18-22 minutes until a toothpick inserted comes out clean.
Allow to cool 5 minutes, then invert onto the parchment to release.
Optionally, dust with confectioners' sugar before serving.