Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.
In a large bowl, cream together the butter and sugar until light and fluffy.
Beat in the egg and vanilla extract until well combined.
In a separate bowl, whisk together flour, baking soda, and salt. Gradually add the dry ingredients to the wet mixture, mixing until a soft dough forms.
Roll dough into balls (about 1½ tablespoons each) and slightly flatten. Place on baking sheets, leaving space between each.
Top each dough disk with a pineapple ring, gently pressing it down.
Sprinkle a little sugar on top of the pineapple for extra sparkle and caramelization.
Bake for 12–14 minutes, or until edges are golden and the cookies are set.
Let cool on the pan for 5 minutes, then transfer to a wire rack to cool completely.