Preheat oven to 350 degrees F.
Peel the pineapple and remove core. Slice into (1-inch) thick circles.
In a small saucepan melt butter with 1 tablespoon of water and add light brown sugar. Stir well with a whisk over medium heat until the sugar is completely dissolved and you have a nice smooth caramel, about 3 to 4 minutes. Pour into a round 9 1/2-inch nonstick cake pan. Arrange pineapple circles evenly in the caramel, (1 in the center and 5 around the outside usually works), and press down so they are submerged in the caramel. Place 1 maraschino cherry in the center of each pineapple ring. Make the batter: Sift flour and baking powder together. In a stand mixer cream butter and granulated sugar until light and fluffy, about 4 minutes. With mixer on low, add eggs 1 at a time. Add half the buttermilk and vanilla then half the flour. Add remaining buttermilk and then remaining flour. Pour the batter into the cake pan over the caramel and pineapple. Spread out evenly with a rubber spatula. Place the cake pan on a roasting tray to catch any caramel that may bubble over and bake in the oven for approx 1 hour. The cake should be nice and golden on top and puffed up slightly. When gently pressed in the center it should bounce back. Allow to cool slightly, (about 1 minute), before inverting onto a cake plate. Dust very lightly with confectioners' sugar and serve each slice with a scoop of yogurt gelato.