Preheat oven to 350°F (175°C).

Melt butter in a 9-inch cast iron skillet or cake pan over medium heat.

Stir in brown sugar until dissolved. Remove from heat.

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

In a medium bowl, whisk together flour, baking powder, and salt.

In a large bowl, cream together butter and sugar until light and fluffy.

Beat in eggs one at a time, then stir in vanilla extract.

Gradually add the dry ingredients to the wet ingredients, alternating with the milk, beginning and ending with the dry ingredients. Mix until just combined.

Pour the cake batter evenly over the pineapple and caramel mixture.

Bake for 40-45 minutes, or until a wooden skewer inserted into the center comes out clean.

Let the cake cool in the pan for 10 minutes before inverting onto a serving plate.

Serve warm or at room temperature.