Preheat your oven to 350°F (175°C).
In your 9x13 inch baking pan, melt 1/2 cup of the unsalted butter over low heat. Once melted, sprinkle the brown sugar evenly over the butter, creating a caramel base. Arrange the pineapple rings on top of the brown sugar, and place a maraschino cherry in the center of each pineapple ring, reserving some cherries for later decoration.
In a mixing bowl, combine the yellow cake mix, the remaining 1/2 cup of melted butter, and the drained crushed pineapple. Mix until well combined and smooth.
Carefully pour the cake batter over the pineapple and cherry layer in the baking pan, spreading it evenly with a spatula.
Place the pan in the preheated oven and bake for 30-35 minutes, or until the cake is golden brown and a toothpick inserted in the center comes out clean.
Once baked, remove the cake from the oven and let it cool in the pan for about 10 minutes. After cooling, carefully invert the cake onto a large serving platter.
Slice your cake and serve warm or at room temperature.
