Preheat oven to 350F.
1 cup cold unsalted butter, diced
1 cup granulated sugar
1 cup firmly packed brown sugar
1 cup peanut butter
1 tsp vanilla
3 cups flour
2 tsp baking soda
½ tsp salt
Cream butter and sugars in a mixer on high speed, scraping down the sides of the bowl often. Beat for about 3 minutes, until light and fluffy. With the mixer on low, add the eggs and vanilla, then add the peanut butter and mix well. Add the flour, baking soda, and salt and mix on low speed until all the ingredients are incorporated. Increase the speed to medium and mix just until the dough is smooth.
Using a small ice cream scoop(or a tablespoon) form the dough into ½ inch balls and place on greased cookie sheet. Flatten cookies with a fork. Bake just until golden brown, about 10 minutes. Let cookies cool about 5 minutes and transfer to a rack to cool completely.