Preheat oven to 350 degrees F. Grease an 11 x 15-inch jellyroll pan.
In a mixing bowl, cream together butter and shortening. Add sugars and beat until light and fluffy. Add eggs, one at a time, beating well after each addition. Add vanilla, mix thoroughly.
Stir in flour, baking soda and salt. When well combined, add chocolate chips.
Spread cookie dough into prepared pan and bake 25 to 30 minutes until golden brown. Cool and cut into bars.