Step 1: Prepare the Pickle-Brined Liquid (Optional, but Recommended). In a small bowl, combine the dill pickle brine and water. Set aside

Step 2: Preheat Oven and Prepare Pan. Preheat the oven to 350°F (175°C). Spray a 9×13-inch baking pan with baking spray with flour. Line the bottom with parchment paper; do not spray again.

Step 3: Prepare Pineapple. Drain the pineapple slices and reserve the liquid. Pat the slices dry with paper towels.

Step 4: Combine Pineapple and Dry Ingredients. Place the pineapple in a large bowl and sprinkle with 2 tablespoons of sugar and the cornstarch, tossing to coat.

Step 5: Arrange Pineapple in Pan. Place the pineapple in the prepared pan. Add the cherries to the pineapple centers.

Step 6: Make the Caramel. In a medium stainless-steel skillet, melt ¾ cup of the butter over medium heat; stir in the brown sugar and ½ teaspoon of salt. Bring the mixture to a simmer; cook until the sugar is melted and fragrant, about 3 minutes.  

Step 7: Add Brined Liquid. Slowly pour in 3 tablespoons of the brined liquid mixture, whisk until combined and smooth.

Step 8: Pour Caramel over Pineapple. Pour the caramel over the pineapple.

Step 9: Make the Cake Batter – Cream Butter and Sugar. In the bowl of a stand mixer, beat the remaining 1 cup of butter, the remaining 2 cups of granulated sugar, vanilla, and dill pickle powder with a mixer at medium speed until creamy, 2 to 3 minutes, stopping occasionally to scrape sides of bowl.

Step 10: Add Eggs. Add the eggs, one at a time, beating well after each addition.

Step 11: Whisk Dry Ingredients. In a medium bowl, whisk together the flour, baking powder, baking soda, and the remaining ½ teaspoon of salt.

Step 12: Alternate Adding Dry Ingredients and Sour Cream. Gradually add the flour mixture to the butter mixture alternately with the sour cream, beginning and ending with the flour mixture, beating just until combined after each addition.

Step 13: Spread Batter over Pineapple. Carefully dollop the batter onto the pineapple in the pan and gently spread it with an offset spatula, making sure not to press too hard or move the pineapple.

Step 14: Bake. Bake for 30 minutes.

Step 15: Add Foil Tent. Place a piece of foil on top of the cake to prevent excess browning

Step 16: Continue Baking. and bake until a wooden pick comes out clean, 15 to 20 minutes more.

Step 17: Cool. Remove the foil and let the cake cool in the pan on a wire rack for 10 minutes.

Step 18: Invert Cake. Run a knife around the sides of the cake to loosen; carefully invert the cake onto a serving plate, removing the parchment.

Step 19: Cool and Serve. Let cool. Serve warm, room temperature, or cold with ice cream or whipped cream.