Sweet, buttery, classic pineapple upside down cake made even better with a tangy twist of natural key lime flavor.
Preheat oven to 350 degrees. Add butter from topping ingredients into a non-stick or prepared loaf pan and place in oven to melt for a couple of minutes.
Meanwhile, combine flour, sea salt and baking powder, baking soda in one bowl. Add the zest from four key limes to this mixture and stir to dredge in the flour.
In another bowl, combine pineapple juice, key lime juice, butter, brown sugar, vanilla extract, milk, and egg. Stir until uniform. Add wet mixture to dry mixture and stir well so that no dry pockets remain.
Carefully remove loaf pan from oven and mix brown sugar in with melted butter to create topping. Spread crushed pineapple into mixture then arrange cherries on top and gently push them through the crushed pineapple so that they touch the bottom of the pan.
Carefully pour cake batter into pan with topping. Place in oven and bake for about 40 minutes or until a toothpick inserted into the center of the cake comes out clean.
Let cake sit for about 10 minutes then run a butter knife around the edges of the cake to release any sticky parts from the pan. Invert cake onto a plate by placing the plate on top of the pan and gently flipping.
Serve warm and refrigerate any leftovers.