Pulse oats in a food processor until semi-fine or fine.

In a small mixing bowl, add the oats, flour, baking soda, salt and cinnamon. Mix thoroughly together with a rubbers spatula or wooden spoon.

To a medium-sized mixing bowl, add butter, both sugars. Cream together using an electric hand mixer. Add vanilla extract, lemon juice and eggs. Mix until you have a smooth mixture. Be sure to scrape the bottom of the bottom of the bowl with a spatula at least once.

Add the dry ingredients to the wet ingredients and mix with a spatula, being careful not to overmix. Drop in the chocolate chips and walnuts and mix until both are evenly distributed throughout the cookie dough. Again, be careful not to overmix or they will have a cake-like texture.

Using a large cookie scoop (3 tablespoons or you can use a medium-sized one to make even more cookies), scoop cookie dough onto a lined baking sheet. Freeze or refrigerate the cookie dough for at least 2 to 4 hours or overnight even.

To bake: Heat oven to 350 degrees F. Place cookie dough portions onto baking sheet lined with parchment paper or a Silpat at least 1 1/2 to 2 inches apart. Bake for 13 to 14  minutes or until desired doneness (for smaller cookies, bake for 12 to 13 minutes).

Allow to cool completely on a cooling rack if storing. Store in a sealed container with a slice of sandwich bread to ensure softness of cookies.