Preheat oven to 325⁰F. Using a mixer, beat together the butter and sugars until creamy. Add the eggs and mix well. Then add the peanut butter and vanilla and beat until well mixed.
Sift the flour, cocoa powder, and baking soda together and add to the peanut butter mixture. Mix until well blended.
Using a medium-sized cookie scoop, place rounded dough scoops (about the size of walnuts) 3 inches apart on a cookie sheet lined with parchment paper. Flatten the cookies with a fork. Bake for 12-15 minutes or until set but not overly brown.
Remove from the oven and let the cookies cool for 3 to 4 minutes, and then move them to a rack to cool.
Notes
Shaping Cookies
If you don't have a cookie scoop, take a walnut-sized amount of cookie dough and roll it into a ball. Then press crisscross with a fork.If the dough is difficult to handle when rolling by hand, chill it in the refrigerator for a few minutes until it is easy to roll into balls.
Variations
Mix in 1 cup of peanut butter chips or chocolate chips to the finished dough for a variation on this recipe. If mixing in both types of chips, use 1/2 cup of each.