Preheat oven to 350°F (175°C). Grease and flour a 9-inch round cake pan.

For the topping: Melt 1/2 cup butter in a small saucepan. Stir in the brown sugar until well combined. Pour this mixture evenly into the bottom of the prepared cake pan.

Arrange the drained pineapple rings over the brown sugar mixture. Place a maraschino cherry in the center of each pineapple ring.

For the cake batter: In a medium bowl, whisk together flour, baking powder, and salt. Set aside.

In a large bowl, cream together the softened 1/2 cup butter and granulated sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla extract.

In a small bowl, whisk together the milk and reserved pineapple juice. Add the dry ingredients and the wet ingredients alternately to the butter mixture, beginning and ending with the dry ingredients. Mix until just combined; do not overmix.

Gently pour the cake batter over the pineapple and caramel topping in the prepared pan, spreading evenly.

Bake for 35-40 minutes, or until a wooden skewer inserted into the center of the cake comes out clean. Allow the cake to cool in the pan for 10 minutes.

Carefully invert the cake onto a serving platter. Let it cool completely before slicing and serving.