Preheat your oven to 325 degrees. Combine the flours and baking powder and sit it to the side.
Using a hand or stand mixer, mix the butter and sugar on low speed until light and fluffy (approximately 5 minutes). Then add the Pineapple extract or emulsion and mix.
Add the eggs to the bowl one at a time, mixing well after each addition before adding the next egg.
Mix in the flour mixture 1 c at a time alternating with the buttermilk beginning and ending with the flour mixture.
In a bowl, mix together your brown sugar, melted butter, and pineapple juice.
Spray a 18-cup bundt pan with baking spray. Then pour the mixture into the bottom of your prepared pan.
Add your pineapple rings around the bottom and sides of the pan and place a cherry in the center of each pineapple ring.
Pour the batter into the pan and spread it evenly.
Place the cake in the oven and bake for about an hour and 30 minutes. (Bake it longer if needed). The cake is done once an inserted toothpick comes out clean.
Remove the cake from the oven and allow it to cool for about 10-15 minutes before removing it from the pan. Allow the cake to cool before serving.