Pre heat oven at 350F.
In a bowl sieve all-purpose flour, salt, baking powder and cinnamon powder. Mix it together, keep aside.
In another large bowl beat eggs until creamed and fluffy, for about 2 minutes. Add white sugar and brown sugar, beat for a minute.
Add pineapple juice, vanilla extract (or rum if using), beat for few seconds to combine.
Now add dry ingredients. Whisk until combined. DO NOT over beat cake batter.
Keep batter aside.
Place pineapple rings on a tray lined with kitchen paper towel. Dab the rings dry with a paper towel on top. If you are using real maraschino cherries, place that too on paper towel to dry out excess liquid.
In a sauce pan add butter, brown sugar, salt and vanilla extract.
Whisk together and heat it until brown sugar is dissolved.
Remove sauce pan from heat and let it sit for few minutes.
Spray generous oil on muffin trays.
Pour a tablespoon of warm brown sugar-butter syrup at the bottom. (Note- I used regular muffin tray). For jumbo muffin trays you’ll need to add 2 tablespoon of brown sugar butter syrup.
Place pineapple rings on it.
Add halved cherry or full cherry (pitted) in the hole of pineapple rings.
Pour cake mix over to fill muffin tray ¾ of the way full.
Bake in pre-heated oven at 350F for 20 to 25 minutes(for jumbo muffin trays) or until toothpick comes out clean.
Note: cooking time will vary if use switch to regular muffin trays. Keep a close watch. Baking in regular muffin trays will need somewhere between 15 to 18 minutes. Check for done with toothpick test.
Pull them out of the oven and let it sit for 5 to 8 minutes.
Loosen the edges with butter knife. Place a cookie sheet on top of the muffin trays and flip them over. Mini pineapple upside-down cakes will come out clean onto the cookie sheet.