Heat oven to 350F/180C
In a 13 x 9"square pan, melt the butter in the oven
Sprinkle the brown sugar evenly over the butter
Arrange pineapple slices on the brown sugar
Place a cherry in the center of each pineapple slice
(you can place the rest of the cherries around the slices, pressing gently into the brown sugar)
Add enough water to the pineapple juice to measure 1 cup
Make the cake batter as directed, using the pineapple juice mixture instead of water
Pour the batter over the pineapple and cherries
Bake 40 to 48 minutes (or until the cake is golden and a toothpick comes out clean)
Remove from the oven and immediately run a knife around the side of the pan to loosen the cake
Place a heatproof plate upside down on the pan and using oven mitts turn the plate and pan over
Leave the pan on top of the cake for 5 minutes so that the brown sugar and butter drizzle over the cake
Remove the pan and cool for 30 minutes
You can serve the cake warm or cool
Store covered in the fridge
Easy as Pie!