Preheat oven to 350°F (175°C) and grease a 12-cup muffin tin well. Beat the softened butter and granulated sugar with an electric mixer for 2 minutes until pale and fluffy.

Beat in the egg and vanilla until the mixture is smooth and glossy, about 1 minute.

Add the flour, baking powder, and salt all at once and stir just until a soft dough forms, about 30 seconds.

Stir the melted butter and brown sugar together, then spoon a teaspoon into the bottom of each muffin cup. Press a pineapple ring in and place a cherry in the center.

Scoop a tablespoon of dough, roll it into a ball, flatten it, and lay it over each pineapple ring. You will have 10 dough balls.

Bake for 14 to 16 minutes, until the cookies are set and just golden at the edges. Cool in the pan for 5 minutes, then invert onto a board and serve warm.