In a medium bowl, whisk together 1 3/4 cups all-purpose flour, 1 teaspoon baking soda, and 1/2 teaspoon salt. Set aside.
In a large mixing bowl, cream together 1/2 cup unsalted butter and 1/2 cup creamy peanut butter until smooth and fluffy.
Add 1 cup granulated sugar and 1/2 cup packed light brown sugar. Beat until light and fluffy.
Add 1 large egg, 1 tablespoon milk, and 1 teaspoon pure vanilla extract. Beat until combined.
Gradually add in the flour mixture and mix on low until just combined.
Wrap the dough in plastic wrap and chill in the refrigerator for at least 30 minutes.
While the dough chills, place the Hershey's Kisses in the freezer.
Preheat the oven to 350 degrees F (175 degrees C). Line a large baking sheet with parchment paper.
Roll the chilled dough into balls and coat in sugar.
Place the dough balls on the baking sheet, about 2 inches apart. Bake until edges start to crack, about 8 to 9 minutes.
Press a frozen Hershey's Kiss into the center of each cookie and return to the oven for 2 more minutes.
Cool on the baking sheet for 2 to 3 minutes before transferring to a cooling rack.
