To the bowl of a stand mixer, add the butter and sugar. Cream together until fluffy.
Add the eggs, extract, and sour cream mixing until evenly combined.
In a medium mixing bowl, add the flour, baking powder, cornstarch, and salt. Using a fork, stir together until evenly combined. While mixing on low speed, add these dry ingredients to the wet, slowly, just until you've added it all and the dough's just combined.
In another small mixing bowl, stir together the melted butter & brown sugar until evenly combined.
Lightly spray a cupcake pan with non stick spray. Add a tablespoon of the brown sugar mixture to the bottom of each cavity. Spread it slightly to cover the bottom. Add the pineapple slice on top of the brown sugar and the cherry in the center of the pineapple.
Add about 3 tablespoons of dough to each cavity, using a spatula or the back of a spoon to flatten/spread it out evenly.
Bake the cookies at 350 degrees for 25 minutes, or until the edges are golden brown and the brown sugar is bubbling up the sides. Remove the pan from the oven, and let rest for 10 minutes.
One by one, turn the cookies out onto a wax paper covered surface. If a pineapple slice sticks to the pan, just pick it up and reposition it onto the cookie cake.
Let the cookie cakes cool completely before serving & enjoying!