Preheat the oven to 350°F (175°C).
In a medium saucepan, melt the butter over medium heat. Once melted, add the brown sugar and stir until combined. Cook for an additional minute until it starts to bubble.
Pour the butter-brown sugar mixture into the bottom of the cake pan. Arrange the drained pineapple slices evenly over the mixture and place a maraschino cherry in the center of each pineapple ring if using.
In a mixing bowl, combine the flour, granulated sugar, baking powder, and salt.
In another bowl, whisk together the milk, eggs, vanilla extract, and melted butter (if not using the butter from the pan).
Gradually add the wet ingredients to the dry ingredients, mixing until just combined.
Pour the batter evenly over the pineapple layer in the cake pan.
Bake in the preheated oven for 35-40 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, remove from the oven and let the cake cool in the pan for about 10 minutes.
Invert the cake onto a serving plate while still warm. Carefully lift the pan off to reveal the pineapple topping.