Combine flour, baking soda, salt and oats. Set aside.
In the bowl of an electric stand mixer, beat butter and brown sugar until creamy, about 2 minutes. Add in eggs, mixing between each. Mix in milk and vanilla.
Add flour mixture into bowl and mix well. Scrape sides and bottom of bowl to ensure all the ingredients are well incorporated.
Stir in chocolate chips and nuts.
Press dough into bottom of prepared pan. Bake 28 – 32 minutes or light golden brown. Let cool completely before cutting into bars.