Preheat your oven to 350°F (175°C) and line a large baking sheet with parchment paper.

In a large mixing bowl, cream together butter and sugar on medium speed for 2-3 minutes until fluffy and pale.

Mix in egg yolks and vanilla extract until fully incorporated, about 1 minute.

Gradually add flour, mixing on low until a soft dough forms.

Scoop out teaspoon-sized portions of the dough, roll into balls, and coat each ball in coarse sanding sugar.

Arrange the balls on the baking sheet, spacing them 2 inches apart, and gently press a candy piece into the center of each.

Bake for 8-10 minutes until bottoms are lightly golden and tops feel set.

Cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.