Preheat the oven:
Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone baking mat.
Cream the butter and sugar:
In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy. This should take about 2-3 minutes.
Add egg and vanilla:
Beat in the egg and vanilla extract until well combined.
Mix dry ingredients:
In a separate bowl, whisk together the flour, baking powder, and salt.
Combine wet and dry ingredients:
Gradually add the dry ingredients to the butter mixture, mixing until a soft dough forms. Be careful not to overmix.
Shape the cookies:
Roll the dough into small balls, about 1 tablespoon each. Place them on the prepared baking sheet, spacing them about 2 inches apart.
Flatten and decorate:
Gently flatten each dough ball with the palm of your hand. Press 5 almond slices into the top of each cookie in a star pattern to resemble a sand dollar.
Bake:
Bake the cookies in the preheated oven for 10–12 minutes, or until the edges are lightly golden. Be careful not to overbake, as you want the cookies to stay soft.
Cool and dust:
Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely. Once cooled, dust the tops lightly with powdered sugar to give them a sandy appearance.
Serve:
Arrange the sand dollar cookies on a platter and enjoy!