Preheat oven to 350 degrees F. Line a couple of cookie sheets with parchment paper.

Beat butter, shortening and both sugars with an electric mixer until very lightly and fluffy – Sunset recommends up to 5 minutes, so you might want to do this in a stand mixer. Add eggs, one at a time, beating well after each addition. Beat in vanilla and lemon juice.

Stir flour, baking soda, salt, cinnamon (if using), and oats together in a separate bowl. Stir flour mixture into sugar mixture. When well combined, stir in the chocolate chips and walnuts.

Use a scant ¼ cup of dough for each cookie. Drop dough onto cookie sheets, spacing about 3 inches between each cookie, and bake at 350 degrees F. for 16-18 minutes OR, for softer cookies, bake at 325 degrees F. for 17 to 19 minutes.

I always use the 350 degree temp. Also, for better texture, chill the pre-formed balls of dough. Just scoop them as directed, put on a dinner plate, cover with plastic wrap and chill until ready to bake.