Whisk dry ingredients together in a separate bowl.
Cream butter with sugars.
Beat in eggs and vanilla.
Add in the dry ingredients.
Mix in the oatmeal followed by your desired additions.
Using a medium cookie scoop, place cookies about 2 inches apart on parchment-lined baking sheet.
Bake in a 350 degree oven for about 14 minutes. Cool slightly then remove them to cooling rack. This makes about 5 dozen cookies. Store in a sealed container or Ziploc bag.