Preheat your oven to 350°F (175°C).
In a saucepan, melt the butter over medium heat. Once melted, remove from heat and stir in the brown sugar until combined. Pour the mixture into the bottom of your 9-inch round cake pan, spreading it evenly.
Arrange the pineapple slices on top of the brown sugar mixture, and place a maraschino cherry in the center of each pineapple slice.
In a mixing bowl, combine the flour, granulated sugar, baking powder, and salt. Mix well.
In another bowl, beat the eggs, vanilla extract, and reserved pineapple juice until well combined. Then, add the milk and melted butter to the mixture.
Gradually add the wet ingredients to the dry ingredients, mixing until just combined. Avoid overmixing.
Pour the batter evenly over the pineapple and brown sugar layer in the cake pan.
Bake in the preheated oven for 45 minutes, or until a toothpick inserted in the center comes out clean.
Once baked, let the cake cool in the pan for about 10 minutes. Then, carefully invert the cake onto a serving plate, allowing the pineapple topping to be on top.