These are, hands down, the best oatmeal chocolate chip cookies I have ever made and probably the best I have ever eaten. Granted, I actually make things that I like more than these (sometimes you feel like a muffin, not a cookie), but I have never seen someone not reach for a second cookies straight away. They are fantastic - slightly crispy on the edges with a nice and chewy center. They are buttery, without being greasy at all, and perfectly balanced. The cookies have just the right amount of chocolate chips to appease any chocolate lover, but not so much that the flavors of the oats and vanilla are drowned out.
I could go on about the taste, but I'll refrain.
The cookies are from The Frog Commissary Cookbook, a book of the recipes from a very popular local restaurant called "Frog" in Philadelphia in the 1970s. As I have family out in that area, I suspect that more than one relative of mine frequented the restaurant, which is probably how my mother ended up with a copy of the cookbook. She started making the cookies and, after a time, so did I.
The book says that the restaurant would "sell this cookie the way that McDonald's sells burgers: they fly out the door." They also note that they were "irresistible," even to employees who were around them every day.
Oatmeal cookies hardy make a good "cooking school" entry in terms of method because almost everyone knows how to make a simple drop-cookie already. They fit in, however, because this is a cookie that everyone needs to have in their repertoire.
Trust me.

Oatmeal Chocolate Chip Cookies
(from The Frog Commissary Cookbook)

1 cup butter, room temperature

1 cup sugar

1 cup brown sugar

2 large eggs

2 tbsp milk

2 tsp vanilla extract

2 cups all-purpose flour

1 tsp baking soda

1 tsp baking powder

1 tsp salt

2 1/2 cups oats (rolled or "quick," but not "instant")

2 cups chocolate chips (about 12-oz.)