Step 1: Preheat your oven to 350°F (175°C). Generously butter a 9-inch round cake pan. Sprinkle 1/2 cup of packed light brown sugar evenly over the bottom of the pan.
Step 2: Arrange the drained pineapple rings in a single layer over the brown sugar in the pan. Place one whole ring in the center and arrange the others around it. Place half a maraschino cherry in the center of each pineapple ring.
Step 3: In a medium bowl, whisk together the dry ingredients: 1 ½ cups all-purpose flour, 1 ½ teaspoons baking powder, and ¼ teaspoon salt. Set aside.
Step 4: In a large bowl, using an electric mixer, cream together 1/2 cup softened unsalted butter and 1 cup granulated sugar until light and fluffy. Beat in 2 large eggs, one at a time, mixing well after each addition. Stir in 1 teaspoon vanilla extract.
Step 5: Gradually add the dry ingredients to the wet ingredients, alternating with 1/2 cup of the reserved pineapple juice. Begin and end with the dry ingredients. Mix on low speed until just combined, being careful not to overmix.
Step 6: Carefully pour the cake batter over the pineapple and cherry layer in the prepared pan. Gently spread the batter evenly. Bake for 40-45 minutes, or until a wooden skewer inserted into the center of the cake comes out clean.
Step 7: As soon as you remove the cake from the oven, place a serving platter upside down over the cake pan. Firmly grasp both the pan and the platter, and swiftly invert them. Let the cake sit inverted for 5-10 minutes before carefully lifting the cake pan. If any fruit sticks, gently replace it. Let the cake cool for at least 30 minutes before slicing and serving.