In a large bowl of an electric mixer, beat butter until light and fluffy, about 3 minutes. Add both sugars and mix until no granules remain, about 5 minutes. Add peanut butter and mix until combined. Add eggs; continue to beat on high speed for 1 minute. In a large bowl, combine flour, baking soda and salt. Slowly add flour mixture to butter mixture; stir until well-blended. Drop dough by heaping tablespoonsful onto greased baking sheets. Flatten dough with palm of hand to form 3-inch circles that are 1/4 inch thick. Bake cookies for 10 to 12 minutes or until lightly browned on the bottom. Makes 9 dozen cookies