Place butter in a large bowl, and beat butter with a mixer until light and fluffy. Add sugars a little at a time and continue to beat until fully incorporated and fluffy. Add eggs 1 at a time, beating well to incorporate. Add vanilla.

In a separate bowl sift flour, baking soda and salt into a medium bowl. Add oats and blend well.

Pour dry mixture into the wet mixture and stir with rubber spatula until well incorporated. Add chocolate and nuts.

Place mixture in refrigerator and allow to rest for at least 12 hours. When ready to bake cookies, preheat oven to 350 – 375 degrees F. Grease cookie sheets or line with parchment.

Using a small ice cream scoop or 1/4 – 1/3 cup measuring cups, scoop cookies onto the sheets, leaving about 1-1/2 – 2 inches between cookies. This will make thicker cookies. If you prefer thinner cookies, flatten them with the back of a spoon or your hand.

Bake in the middle of the oven. Check cookies at 9 minutes. Depending on oven and size of cookies, it will take between 9 and 12 minutes for them to be ready.

Place baking sheet on cooling rack for 2 minutes. Slide cookies on parchment onto cooling rack and allow to cool. Store in an airtight container.

I have cut the brown sugar in the original recipe by 1/4 cup. If you don’t want a really sweet cookie, you could cut the sugar by another 1/4 cup. Conversely, if you like a sweeter cookie, add an additional 1/4 cup brown sugar.