Heat oven to 350 degrees. Place butter and milk for the batter in a small saucepan over medium heat. Warm the mixture, stirring occasionally, until butter melts, the transfer to a small bowl to cool.
Meanwhile, prepare the pineapple topping. Into each cup of a 12 cup muffin pan, add 1/2 tablespoon of unmelted butter, the evenly sprinkle 1 tablespoon of brown sugar over the bottom. Place the pan in the oven until butter melts, about 3 minutes.
Halve each maraschino cherry, then cut the pineapple rings into quarters. Place a cherry half, sliced side up, in the center of each cup and lay pineapple quarters on each side. Press the fruit down gently into the butter/sugar mixture, then set prepared pan aside.
Finish making the batter. In a medium size bowl, combine the flour,baking powder, salt and stir the ingredients with a fork until they are evenly blended. In a large bowl, whisk together the eggs, sugar, and vanilla extract until smooth. Add the flour mixture to the egg mixture until the flour is fully incorporated. Add the milk-butter mixture and stir well to combine the ingredients into a smooth batter.
Pour the batter into the muffin pan, dividing it evenly among all the cups. Bake the cupcakes until they're lightly browned, dry around the edges, and pulling away from the pan a little, about 25 minutes.
Transfer the pan to a rack to cool for 5 minutes. Use a butter knife to carefully loosen each cupcake from the edges and bottom of the pan, then place a cookie sheet over the top. Invert the pan, turning the cupcakes onto the cookie sheet, then transfer them back to the rack to cool completely. Serve the cupcakes at room temperature. Make 12 cupcakes.