Heat 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 an electric mixer, add butter and peanut butter. Beat on medium speed 2 minutes until completely incorporated.
Add the brown and granulated sugars and beat an additional 2-3 minutes or until smooth, creamy and paler in color.
Add the egg and vanilla and beat another 1 minute.
In another large mixing bowl, whisk together flour, ½ teaspoon baking soda, table salt, sea salt and 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 add the peanut butter chips, if using.
Stir the dough gently just until all flour is incorporated.
Use an 1.5” 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.
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 at 350°F or until the edges of the cookies are set.
Transfer the cookies to a cooling rack and…