How to make it:

The night before:
In a large mixing bowl, cream the butter and sugars with an electric mixer on medium speed for 3 minutes. You want it to be light and fluffy, all the sugar is dissolved and incorporated. Add in the eggs one at a time, beating another 2 minutes total. 

In a medium mixing bowl, combine the dry ingredients and stir to combine. Flour tip: fluff the flour with a fork, then spoon into a measuring cup (don't scoop!), then level off.

Pour half of the dry ingredients into the wet mixture and mix with a spatula to combine; add the remaining and mix just until incorporated. You want the oats to be as whole as possible. Broken and crumbly oats can lead to a mucky texture.

Cover with cling wrap and refrigerate overnight.

Baking day:
Preheat oven to 350° F.

Line large baking sheets with parchment paper, or use nonstick pans. Using a cookie scoop, place 12 dough balls on prepared sheet.

Bake for 8-10 minutes, or until just the edges become light golden brown. They'll look a tad undone in the middle with golden edges. Cool on the baking sheet for 3-5 minutes then transfer cookies to a wire rack to cool completely.

Cookies stay fresh covered at room temperature for up to 1 week.