Preheat the Oven: Preheat your oven to 375°F (190°C).
Sift Dry Ingredients: In a sifter, add the flour, baking soda, and salt. Sift these ingredients together into a bowl.
Cream Wet Ingredients: In a large bowl, use a mixer to cream together the butter, smooth peanut butter, sugar, and brown sugar.
Add Egg and Flavorings: To the creamed mixture, add the egg, milk, and vanilla. Blend well.
Combine Wet and Dry Ingredients: Gradually add the dry ingredients to the wet mixture and blend until it forms a dough.
Shape and Sugar Coat: Take small portions of the dough and roll them into one-inch balls. Then, coat each ball in sugar.
Prepare for Baking: Cover a baking tray with parchment paper and place the dough balls evenly spaced on the tray.
Bake: Bake in the preheated oven for 8 minutes.
Add Hershey's Kisses: Immediately after removing the cookies from the oven, gently press a Hershey's Kiss into the center of each cookie.