Preheat your oven to 350°F (175°C). Grease the 9-inch round cake pan with butter.

Melt the butter in a saucepan over low heat. Stir in the brown sugar until it dissolves, then pour this mixture into the prepared cake pan.

Place the pineapple slices on top of the butter mixture, making sure they are evenly spaced. Use maraschino cherries to fill the center of each pineapple ring.

In a mixing bowl, combine the Duncan Hines cake mix, vegetable oil, eggs, and water. Beat with an electric mixer until smooth, about 2 minutes.

Carefully pour the cake batter over the arranged pineapple and cherries in the pan. Spread it evenly.

Bake in the preheated oven for 35 minutes or until a toothpick inserted into the center comes out clean.

Remove the cake from the oven and let it cool in the pan for about 10 minutes.

Place a serving plate upside down over the pan and carefully flip it to release the cake.