Preheat the oven to 350 degrees Fahrenheit.

Make the topping. Place ½ tablespoon of the butter in each of the cups of a Lodge Cast Iron Mini Cake Pan. Place in the oven to melt, about 1 minute. Remove the pan from the oven and sprinkle 1 teaspoon brown sugar evenly over the bottom of each cup. Place a pineapple ring in each cup. Place a cherry in the center of each ring. Set aside.

Make the cake batter. Whisk together the flour, baking powder, salt, cardamom, and cinnamon in a small bowl.

Whisk together the milk, vanilla, and rum in a small bowl.

In a large bowl, using an electric mixer on high speed, beat the butter until creamy. With the mixer running on low speed, gradually add the granulated sugar. Increase the speed to high and beat until the mixture is light and fluffy, about 5 minutes. Add the egg and beat well. Add half the flour mixture and beat on low speed until blended. Add the milk mixture and beat until smooth. Add the remaining flour mixture and beat until smooth. Increase the speed to high and beat for 1 minute, stopping once to scrape down the side of the bowl with a rubber spatula.

Gently spoon the batter into the cups of the pan, taking care to keep the pineapple rings centered. Bake until the cakes are golden brown and spring back when touched lightly in the center, about 20 minutes.

While the mini cakes are baking, make the caramel sauce.

Add brown sugar, butter, and salt to a cast iron melting pot. Bring to a simmer over medium high heat, stirring often until everything is melted and foamy.

Remove from heat and slowly stir in the cream.

Once cooked, place the mini cake pan on a wire rack to cool for 5 minutes. Run a thin knife around the edge of each cup. With oven mitts, carefully invert the pan onto a large plate by placing the plate over the pan, holding them tightly together, and flipping them over together. Lift off the pan to release the mini cakes.

Pour caramel sauce over mini cakes. Serve warm.