Preheat your oven to 350°F (175°C). Melt the butter and pour it into the bottom of a 9-inch round cake pan, then sprinkle evenly with brown sugar. Place the pan on the stove over medium heat and cook until the mixture bubbles and turns golden, creating a caramel layer.
Arrange pineapple slices in a single layer over the caramel, fitting them snugly in the pan. Place a maraschino cherry in the center of each pineapple ring for a colorful touch.
In a large mixing bowl, whisk together the flour, sugar, eggs, vegetable oil, vanilla extract, and milk until smooth and well combined. The batter should be slightly thick but pourable.
Carefully pour the batter evenly over the arranged pineapple and cherries in the pan, smoothing the top with a spatula if needed.
Bake in the preheated oven for about 40 minutes, or until the cake is golden brown on top and a toothpick inserted in the center comes out clean. The caramel should be bubbling around the edges.
Remove the cake from the oven and let it cool for 10 minutes. Then, carefully invert the cake onto a serving plate, allowing the caramelized fruit to be on top.
Gently lift the pan off, revealing the glossy, sticky fruit topping and golden cake base. Serve warm or at room temperature to enjoy the gooey caramel and tender fruit.
