Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper or silicone baking mats.

In a small bowl, mix the drained crushed pineapple, brown sugar, and melted butter until well combined. Drop small spoonfuls (about 1 teaspoon each) of the pineapple mixture onto the prepared baking sheet, spacing them about 2 inches apart.

In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy (about 2–3 minutes). Beat in the egg and vanilla extract until smooth. In a separate bowl, whisk together the flour, baking powder, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Add 2–3 tablespoons of the reserved pineapple juice to the dough, 1 tablespoon at a time, until the dough reaches a soft, scoopable consistency.

Scoop about 1 tablespoon of cookie dough and roll it into a ball. Place the dough ball directly on top of each pineapple topping dollop. Gently press down on the dough to slightly flatten it and help it adhere to the pineapple layer.

Bake for 10–12 minutes, or until the edges are lightly golden and the cookies are set. Remove from the oven and let the cookies cool on the baking sheet for 5 minutes.

Carefully flip each cookie over using a spatula to reveal the caramelized pineapple topping underneath. Let cool completely before serving.