Preheat oven to 375 degrees.
Combine the butter, brown sugar and white sugar in a large bowl. Beat on medium speed until creamy, scraping the bowl as needed.
Add the eggs and vanilla, beat until well incorporated.
With the mixer on low speed,add the flour, baking soda and salt. Beat until well incorporated. Add the oatmeal and mix well. Stir in the chocolate chips and walnuts.
Press the dough into an ungreased jelly roll pan. Bake 16 - 20 minutes until golden brown. Remove from the oven to a cooling rack, cool completely. Cut into bars.