Preheat oven to 350°F and line 2 large baking sheets with parchment paper. (If not using parchment, do NOT grease the baking sheets.)
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and peanut butter together on medium speed until completely incorporated, about 2 minutes.
½ cup unsalted butter, ½ cup creamy peanut butter
Add the brown and granulated sugars and cream until smooth, creamy, and pale in color, about 2-3 minutes.
½ cup dark brown sugar, ½ cup granulated sugar
Add the egg and vanilla and beat another 1 minute.
1 large egg, 1 teaspoon pure vanilla extract
In another large mixing bowl, whisk the flour, baking soda, salt, and cinnamon together.
1¼ cups all-purpose flour, ½ teaspoon baking soda, ¾ teaspoon kosher salt, 1 teaspoon ground cinnamon
Add the flour mixture to the butter mixture and turn the mixer to low speed. Mix until the flour is almost incorporated. There should be just a little flour visible.
Remove the mixing bowl from the mixer and fold in the peanut butter chips, if using.
1 cup peanut butter baking chips
Stir the dough gently just until all flour is incorporated.
Use a 1½-inch cookie scoop to scoop balls onto the baking sheet 2 inches apart. (If you don’t have a cookie scoop – use about 1½ tablespoons of dough per cookie and roll the dough into balls.)
Lightly sprinkle the cookies with powdered sugar.
¼ cup powdered sugar
To put fork marks into the cookies, gently press the fork onto the cookie dough – being sure to crisscross the fork to get that traditional “peanut butter cookie” appearance.
Bake 9-10 minutes, or until the edges of the cookies are set.
Transfer the cookies to a cooling rack to cool to room temperature.