Grease a rectangle cake pan (Dimensions: 13x9) with oil spray.
Pour melted butter in the pan and spread it out.
Sprinkle brown sugar evenly on top.
Add pineapples. Try to spread them out as best as you can.
Add cranberries as evenly as you can.
Prepare the yellow cake batter, according to box instructions.
Mix in orange zest.
Pour batter on top of cranberry pineapple mixture.
Spread it as evenly as possible with a spatula.
Bake at 350 degrees F for about 40 minutes or until an inserted toothpick in the center comes out clean. The top will have an odd, bumpy, uneven appearance and that's normal.
Remove from oven and let it cool for 10 minutes.
Run a knife along the sides of the cake to loosen it.
Then, gently turn it onto a large cake dish. Tap the cake pan on top to ensure the cake has released fully.
Remove cake pan.
Add swirls of whipped cream on top of your cake, if you like, once it fully cools down. Enjoy!