Cream butter, sugar and brown sugar in bowl of stand mixer on medium speed for about 2 minutes. (See Tip 8)
Add eggs, vanilla and lemon juice with mixer on low speed for 30 seconds. Then medium speed for about 2 minutes or until light and fluffy, scraping down the bowl.
With mixer on low speed, add flour, oats, baking soda, salt and cinnamon, blending for about 45 seconds. Do not overmix.
Remove bowl from mixer and stir in chocolate chips and walnuts.
Portion dough with a scoop (about 3 tablespoons) onto a baking sheet lined with parchment paper about 2 inches apart. (See Tips 9 and 10)
Preheat oven to 300°F. Bake for 20 to 23 minutes, or until edges are golden brown and center is still soft.
Remove from oven and cool on baking sheet for about 1 hour.
You can freeze unbaked cookies, and there’s no need to thaw. Preheat oven to 300°F and place frozen cookies on parchment lined baking sheet about 2 inches apart. Bake until edges are golden brown and center is still soft. (See Tip 11)
Yield: 26 cookies. (See Tip 12)