Heat oven to 375°F and line 2 baking sheets with parchment paper. Set aside.
Whisk the flour, baking soda, baking powder, and salt together in a medium-sized bowl. Set aside.
3 cups all-purpose flour, ½ teaspoon baking soda, ½ teaspoon baking powder, 1 teaspoon kosher salt
In the bowl of a stand mixer fitted with the paddle attachment, cream the butter and peanut butter together until smooth, about 2 minutes.
1 cup unsalted butter, 1 cup creamy peanut butter
Add the brown sugar and granulated sugar and beat until lighter in color and smooth, about 2-3 minutes.
⅔ cup dark brown sugar, ⅔ cup granulated sugar
Add the eggs and vanilla and beat until all ingredients are incorporated and smooth, about 1 minute.
2 large eggs, 2 teaspoons pure vanilla extract
Turn off the mixer and add the flour mixture. Turn the mixer to the lowest speed and mix just until the flour is incorporated.
If the mixture seems too stiff, add 1 tablespoon milk, mixing just until incorporated.
1 tablespoon milk
Cover the dough and refrigerate 30 minutes, or until firm enough to roll into balls.
Shape the dough into ¾-inch balls and place them about 1½ inches apart on the prepared baking sheets. 20 balls work perfectly on a half-sheet baking pan (18x13 inches).
Bake for 8 minutes, remove from the oven, and press a candy kiss in the middle of each cookie. Press down just enough to set the kiss being sure not to press the candy clear to the pan.
2 pounds Hershey’s Kisses
Place the cookies back in the oven and bake an additional 2 minutes.
Transfer the cookies to a cooling rack – remove the cookies from the baking sheet after 2 minutes.