Step 1

In a large bowl, beat 1 cup of sugar with butter with a hand mixer on medium speed until light and fluffy.

Step 2

Add egg, egg yolk, and vanilla, beat until combined. Stop Ince to scrape the bottom and sides of the bowl with a spatula.

Step 3

In another bowl, stir together flour, cocoa powder, baking soda, and salt.

Step 4

Add flour mixture little by little to the butter mixture, and beat until well combined.

Step 5

Cover the dough and refrigerate for at least 1 hour.

Step 6

Preheat oven to 350 degrees F.

Step 7

Divide dough into 20-24 balls, about 1” big. Roll each ball in sugar and place onto a baking sheet covered with parchment paper. Cookies should be 2 inches apart.

Step 8

Bake 9-11 minutes or until lightly browned on the sides.

Step 9

Remove from the oven and cool 2-3 minutes and immediately press a Hershey kiss into the center of each cookie and transfer it to a cooling rack.

Step 10

Cool completely.