Preheat the oven to 350 degrees. Line cookie sheets with parchment.
Cream the brown sugar and butter in a kitchen aid mixer (or use a hand-mixer if that’s all you have) until it turns lighter in color and is fluffy, 3-5 minutes.
Beat in the vanilla and the eggs. Scraping the bowl as you go.
Mix together flour, salt, and baking soda. Add it to the creamed mixture in a couple batches, making sure to start beating on low.
Mix in the oats just until combined.
Drop by tablespoons (I use a roughly tablespooned size cookie scoop) onto a cookie sheet about 2 inches apart.
Bake until dark brown. For a chewy cookie about 12 minutes. For a crisper cookie bake about 15-17 minutes.
Cook for a minute or two on the pan and then move to a wire rack to cool completely.
Stir in a tightly covered container (unless you’re my dad, then slightly crack open the container lid when no one is looking so they get even crisper).