Step 1

In a bowl, whisk together flour, baking soda, and salt. Set aside.

Step 2

In the bowl of a stand mixer fitted with the paddle attachment, or a large bowl with an electric hand mixer, beat butter until smooth. Cream the butter with 1/2 cup granulated sugar and the light brown sugar until light and fluffy. Beat in peanut butter.

Step 3

Scrape the bottom and sides of the mixing bowl. Beat in milk and vanilla, followed by the egg, until combined.

Step 4

Add the flour mixture and mix until a stiff dough forms. Cover the mixing bowl and refrigerate for 30-60 minutes.

Step 5

Preheat oven to 375 degrees F. Place 1/4 cup granulated sugar in a shallow bowl.

Step 6

Scoop the dough into 1-1/4 inch portions (40-42 portions), roll them into balls, and then roll them in the granulated sugar. Place on ungreased baking sheets, 2 inches apart.

Step 7

Bake the cookies 8-10 minutes, until set, lightly brown, and just starting to crack. Don't overbake.

Step 8

As soon as you remove the cookies from the oven, gently press a Hershey's kiss into each center. (The cookies will crack - this is normal and part of their classic appearance.) After about 5 minutes, transfer the cookies to a wire rack to cool completely, at least an hour. (The chocolate should be firm before the cookies are stored.)

Step 9

Store at room temperature in an airtight container for 3-5 days, or freeze for 2-3 months.