1. Preheat the oven to 350°F and line two baking sheets with parchment paper.

2. In a medium bowl, whisk together the flour, baking soda, and salt.

3. In a large bowl, beat the butter, granulated sugar, and brown sugar until light and fluffy.

4. Mix in the egg, vanilla extract, and milk until smooth.

5. Gradually add the dry ingredients and mix just until a soft dough forms.

6. Scoop tablespoon-sized portions of dough and roll them into balls.

7. Roll each dough ball in pastel sanding sugar and place on the prepared baking sheets.

8. Bake for 8 to 10 minutes, until the edges are set and the tops still look soft.

9. Remove from the oven and immediately press one chocolate candy into the center of each cookie.

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