How to Make It
Preheat oven to 350°F. Grease a standard-size nonstick 12-cup muffin pan with cooking spray.
In the bowl of a stand mixer, stir together flour, sugar, baking powder, and salt. Add butter and beat on low speed with paddle attachment until fully incorporated into flour, about 3 minutes.
In a separate bowl, whisk together buttermilk, egg yolks, egg, 2 Tbsp. reserved pineapple juice, oil, and vanilla. Add half of the liquid ingredients to the mixer and beat on medium-low for 2 minutes. Scrape down the sides of the bowl, add remaining liquid ingredients and beat on medium for 3 minutes.
Place 1 teaspoon of brown sugar in each of the muffin cups, using your finger to evenly spread the sugar across the bottoms of each cup. On top of the brown sugar, place three pineapple chunks around the edge of the bottom of each muffin cup. Place a maraschino cherry in the center of each muffin cup. Evenly divide cake batter among muffin cups, dumping batter directly on top of brown sugar, pineapple, and maraschino cherries.
Bake until golden brown and a toothpick inserted comes out clean, 23 to 25 minutes. Remove from oven and immediately run an offset spatula or knife around the edge of each cupcake. Place a baking sheet on top of the muffin pan and quickly flip the baking sheet and muffin pan so that the Pineapple Upside-Down Cupcakes cleanly come out of the pan. Serve warm.