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, whisk together the flour, granulated sugar, softened butter, baking powder, salt, vanilla extract, milk, and egg until smooth.
Pour the batter over the pineapple slices in the cake pan.
Bake for 45 minutes, or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for 5 minutes, then invert it onto a serving plate. Serve warm.