Preheat your oven to 350°F (175°C).
Pour the melted butter into a 9-inch round cake pan. Sprinkle the brown sugar evenly over the butter.
Arrange the pineapple slices on top of the brown sugar. Place a cherry in the center of each pineapple slice.
In a mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.
Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
In another bowl, whisk together the flour, baking powder, and salt. Add this dry mixture to the creamed mixture alternately with the milk, beginning and ending with the dry ingredients.
Spread the batter evenly over the pineapple slices in the cake pan.
Bake in the preheated oven for 45 minutes, or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for about 5 minutes. Run a knife around the edges to loosen, then invert the cake onto a serving plate. Serve warm or at room temperature.