Baking requires that you get certain ratios right, so it makes variations trickier than if you're tossing extra potatoes into a stew. Some baking substitutions are simple. Swapping chocolate chips for butterscotch chips is no big deal. Other substitutions are more problematic.
So if you're not willing to do a lot of experimenting, you're better off finding a good recipe and using that - or making the little changes that don't make a difference.
One cool thing about this book is that it suggests variations and proper amount for those add-ins. For this one, 1 to 1 1/2 cups of chips, nuts, raisins, or whatever else you like. One of my favorite add-ins for oatmeal cookies is butterscotch chips, but in this case I decided to go with the "plain Jane" version of these cookies - no add-ins.
So I've got a lot of baking books. Now I have one more.
1 cup packed dark brown sugar
1/8 cup white sugar
2 teaspoons vanilla extract
1 1/2 cups flour
1 teaspoon baking soda
1 teaspoon cinnamon
1 teaspoon salt
3 cups old-fashioned oats
Preheat the oven to 350 degrees and line a baking sheet with parchment paper.
In a large bowl, cream the butter and sugars until light an fluffy. Add the eggs one at a time and mix well. Stir in the vanilla.
In a separate bowl, combine the flour, baking soda, cinnamon, and salt.
Gradually add the flour mixture to the butter mixture, mixing until fully incorporated. Mix in the oats and any add-ins you like.
Use a spoon or scoop to scoop balls of dough. Place them on the prepared baking sheet about 2 inches apart.
Bake for 12 to 14 minutes, until golden on the edges.