1/4cuppineapple juiceyou can drain it from the can of pineapple
Preheat oven to 350 degrees F. Coat a 9" x 2" cake pan with cooking spray.
For the topping: pour the 1/4 cup of melted butter into the cake pan. Sprinkle 1/3 cup of brown sugar over the top.
Top with pineapple slices and arrange the cherries between and inside of the pineapple slices.
In a medium bowl, mix together the flour, baking powder, baking soda, and salt.
Place the 1/2 cup melted butter, 3/4 cup brown sugar and 1/4 cup granulated sugar in a bowl. Whisk to combine. Add the egg, buttermilk, pineapple juice, and vanilla extract. Stir until just combined. Slowly mix in dry ingredients until smooth.
Spoon the batter into the pan on top of the pineapple and cherries. The batter should not be overflowing from the pan.
If you aren't using a 9x2 inch pan you'll have extra cake batter, which you can bake on the side in a greased loaf pan.
Bake the cake for 40-45 minutes. Check about 30 minutes into the bake time; if it looks like the top of the cake is getting too dark you can cover it with foil.
Cool the cake in the pan for 10 minutes.
Invert the cake and cool for another 20 minutes. Cut into slices and serve.