Preheat the oven to 375 degrees. In a large mixing bowl, with an electric mixer, cream together the butter and sugars until creamy and light in color and texture. Add the eggs one at a time and the vanilla. Continue to mix until incorporated. Then add the baking soda, salt, flour and oats. Continue to mix until cookie dough comes together and all the oats are coated. Then add the chocolate chips and mix slightly until they are all dispersed throughout the dough. Spray a 9x13 pan and pour the dough into the pan and spread evenly throughout the pan. Place in the oven and bake for 33-35 minutes. The tops of the bar will be lightly golden brown but you will not think the center is all the way cooked. You want them to look slightly under done or they will dry out and not be as good. Remove the cooked bars from the oven and let them rest on the counter for 2-3 hours (unless you want to eat it warm with vanilla ice cream--that's also heavenly!). If you want the bars to set up and be able to cut nice squares, you will want it to rest for awhile to set up. These are extremely thick and you want to so that the bars are tender and gooey in the center and not dry and thin. These are bars that are even better the next day once they are totally set up.