Pineapple Upside-Down Donuts

Ingredients:

• 1 can of 600g canned pineapple rings, pour out 1 tsp of juice separately, the rest is not needed
• 165 g butter
• 1 cup brown sugar
• 1 and 3/4 cups flour
• 1 cup granulated sugar
• 1 teaspoon baking powder
• 3/4 teaspoon coarse salt
• 0.5 tsp of soda
• 0.5 cups of sour milk or kefir
• 1/4 cup vegetable oil
• 0.5 tsp vanilla extract
• 1 large egg
• 18 maraschino cherries, stems removed
• Special equipment: metal donut pan with non-stick coating, large pastry bag

Preparation:

1. Preheat oven to 190°C.
   
   Carefully cut the pineapple rings in half from the sides to make thin slices.
2. Melt the butter in a small saucepan, then turn off the heat and stir in the brown sugar until completely dissolved. Spoon 1 tablespoon of the sugar mixture into each well of a metal donut pan, then top with a pineapple slice, pressing firmly.
3. In a medium bowl, whisk together the flour, granulated sugar, baking powder, salt, and baking soda. In a separate bowl, combine the buttermilk, vegetable oil, vanilla, egg, reserved pineapple syrup from the can, and 1/4 cup water. Stir the liquid mixture into the dry mixture and knead until smooth. Transfer to a large pastry bag or resealable plastic bag, snip the corner to create a 2-cm (0.8-inch) opening, and squeeze some of the batter into a donut pan, filling each well almost to the top.
4. Place the pan with the dough on a rimmed baking sheet and bake until a toothpick inserted into the center of a donut comes out clean, about 10 minutes. Cool the donuts in the pan for 5 minutes, then lift them out with an offset spatula and transfer them to a wire rack. Top each donut with a cherry and repeat with the remaining dough two more times.