Pulse the oats in a blender or food processor. In a bowl, combine the oats, flour, baking soda, salt, and cinnamon. Whisk together and set aside.
In the bowl of an electric mixer, add the butter and sugars. Cream until light in color, scraping the bowl as needed. Add the eggs, vanilla, and lemon juice.
Add the flour mixture to the egg mixture and stir by hand until almost combined. Add the walnuts and chocolate chips and stir to finish mixing the dough. Don't overmix!
Let the dough chill for at least 30 minutes or up to overnight.
When ready to bake, preheat the oven to 350F and scoop the dough onto prepared baking sheets 2 inches apart. Bake for 13-15 minutes until done to your liking. Let cool on the baking sheet for 3 minutes, then remove to wire racks to finish cooling.
Eat 5 at once. Enjoy!