Preheat the oven to 350°F (175°C). Lightly grease a 9-inch round cake pan using butter or nonstick spray to prevent sticking.
Begin with the topping. Pour the melted butter evenly into the bottom of the prepared pan. Sprinkle the brown sugar over the butter, covering the base in a uniform layer. Arrange the pineapple rings over the sugar, fitting as many as will comfortably lie flat. Nestle one maraschino cherry in the center of each ring.
In a medium bowl, combine the flour, baking powder, and salt. Stir with a whisk to blend thoroughly, then set the mixture aside.
In a separate large mixing bowl, cream together the softened butter and granulated sugar using an electric mixer until the mixture becomes pale and fluffy, about 2–3 minutes.
Add the eggs one at a time, beating well after each addition. Incorporate the vanilla extract and mix to combine.
Alternately add the dry flour mixture and the milk to the creamed butter mixture, beginning and ending with the dry ingredients. Stir gently after each addition, mixing only until the batter is just combined. Avoid overmixing to maintain a light texture.
Carefully spoon the batter over the arranged fruit in the cake pan, spreading it evenly to cover the fruit layer without disturbing the arrangement.
Transfer the pan to the preheated oven and bake for 40 to 50 minutes. The cake is ready when a toothpick inserted into the center emerges clean.
Once baked, allow the cake to rest in the pan for 10 minutes. Run a thin knife along the sides to loosen the edges. Place a serving platter over the cake pan and invert. Let the pan rest for another minute to allow the topping to release fully, then lift it off gently.
Cut into portions and serve warm or at room temperature. Optional: Accompany with a dollop of whipped cream or a scoop of vanilla ice cream.