My Favorite Oatmeal Cookies

My sister-in-law asked me for a good oatmeal cookie recipe (a couple of weeks ago--sorry it took so long, Jenni) so I'm posting my favorite. I've tried many over the years and have settled on this one. It's a combination between America's Test Kitchen version and a recipe I found in the cookbook: 5 Star Recipes From Well-Known Latter-day Saints. I like the oat to flour ratio (twice as many oats) as well as the amount of butter called for (it's less than most recipes but still enough). This makes a soft chewy cookie, with a lightly crisp outside. I'm partial to chocolate chips and nuts in this recipe, but Craisins and white chocolate chips, peanut butter chips, or butterscotch chips are all very good.
Update 7/26/12
I tried making these with 1/2 cup butter and 1/3 cup pure olive oil and they turned out perfectly when baked right away.  I doubt I'll ever make them with all butter again.  No spread, and slightly crisp edges with chewy centers.  I bet coconut oil would also be a good replacement for some of the butter.
Famous Oatmeal Chocolate Chip Cookies

1 c. butter, softened

1 c. brown sugar

½ c. sugar

2 eggs

1 t. vanilla

1 ¾ c. flour (I use whole wheat pastry flour)

½ t. baking powder

½ t. salt

1 t. cinnamon (optional; I usually don't use it)

3 c. old-fashioned oats

2-3 c. Add-ins (chocolate chips, nuts, Craisins, raisins, other baking chips)

Cream butter and sugars; add eggs and vanilla and beat well. Add flour, baking powder, salt and cinnamon and mix until combined. Add oats and chips. Scoop onto cookie sheet (I use parchment paper--and I use each sheet over and over again) and bake at 350 for 8-10 minutes. For bar cookies, spread batter in ungreased 9x13 pan and bake for approx. 30 minutes. This recipe makes exactly 3 ½ dozen cookies when I use my medium pampered chef cookie scoop.

Tip: If you bake these right away, they spread a little. They're good (my kids don't complain) but I prefer to chill the dough first before baking (as per America's Test Kitchen suggestion). I scoop all the dough onto cookie sheets and refrigerate or freeze before baking. Add an extra minute to the baking time when baking chilled dough.

Note: The above recipe works great for my altitude and my oven. If you are baking at a lower altitude, try using ¼ c. less flour and ¼ c. more sugar and alter baking temperature and time as needed.