Preheat your oven to 350°F / 175°C.
Line a large baking sheet with parchment paper. 2.
In a medium bowl, whisk together the flour, baking soda, baking powder, and salt.
Set aside. 3.
In a large bowl using a stand mixer or hand mixer, cream the softened butter with the granulated and brown sugars until light and fluffy, about 2-3 minutes. 4.
Beat in the eggs one at a time, mixing well after each addition.
Stir in the vanilla extract. 5. Gradually add the dry flour mixture to the wet , mixing on low speed until just combined.
Do not overmix. 6.
Using a wooden spoon or sturdy spatula, fold in the rolled oats, chopped walnuts, and chocolate chips. The dough will be very thick and crumbly. 7.
Drop rounded tablespoonfuls of dough about 2 inches apart onto the prepared baking sheet. 8.
Bake for 12 to 15 minutes, or until the edges are golden brown and the centers are set. 9.
Let the cookies cool on the baking sheet for 5 minutes before carefully transferring them to a wire rack to cool completely.
