Blackberry Upside-Down Cake

Step 1
Preheat the oven to 350 degrees F (175 degrees C). Line a baking sheet with parchment.

Step 2
Melt brown sugar and 2 tablespoons butter together in a saucepan over medium heat. Add blackberries to brown sugar mixture; cook and stir until mixture bubbles, 1 to 3 minutes. Stir 3/4 cup white sugar into berries, crush berries slightly with a fork, and continue cooking until berries are hot and slightly broken-down, about 5 minutes more; remove from heat and pour into a 9-inch cake pan.

Step 3
Beat 1 cup white sugar and 1/2 cup butter together in a bowl with an electric mixer until light and fluffy; beat in eggs.

Step 4
Whisk flour, baking powder, and salt together in a bowl. Alternately stir flour and milk into butter mixture, beginning and ending with the flour mixture. Mix vanilla into batter.

Step 5
Pour batter over blackberry mixture in the 9-inch cake pan. Place cake on prepared baking sheet in case of spillage as it bakes.

Step 6
Bake cake in the preheated oven until cooked through, 35 to 40 minutes. Let cake cool in the pan until warm, but not completely cooled, about 30 minutes. Run a knife along the inside edge of the pan to separate cake from the sides, place a cake plate over the top of the pan, and flip the pan. Lift the pan slowly to release the cake from the pan.