Preheat oven to 300 degrees F. Line a cookie sheet with parchment paper.
Add the 1 cup butter, 3/4 cup plus 1 tablespoon granulated sugar, and 3/4 cup light brown sugar in a large bowl. Beat with a hand mixer on medium for 3 minutes until light and fluffy.
Add the 2 large eggs, 1 1/4 teaspoons vanilla extract, and 1/4 teaspoon freshly squeezed lemon juice. Beat on low until the eggs are incorporated and then turn mixer to medium and continue to beat for an additional 2 minutes until light and fluffy.
Add the 2 1/4 cups all-purpose flour, 1/2 cup old fashioned rolled oats, 1 teaspoon baking soda, 1 teaspoon salt, and 1/8 teaspoon ground cinnamon. Beat just until the dry ingredients are worked into the dough.
Stir in 2 2/3 cups semi-sweet chocolate chips and 1 3/4 cups chopped walnuts until evenly distributed.
Scoop the cookies with a 3 tablespoon cookie scoop onto the prepared cookie sheet about 2 inches apart.
Bake for 20 to 23 minutes or until edges are golden brown and center is still soft.
Remove from the oven and let cool for 10 minutes before transferring to a wire rack.
Store in an airtight container at room temperature.
Notes
I used 1 cup of chopped walnuts and 3/4 cup of chopped pecans.Storage: Store in an airtight container or in a storage bag at room temperature for up to 5 days.