Cream butter and peanut butter with mixer, then add sugars and baking soda. Finally add the egg and vanilla, and blend together.
Stir together the flour and oats, then add to the blended mixture, and stir everything till combined.
Spoon rounded teaspoonfuls about 2 inches apart on a large greased cookie sheet (Or use baking parchment). Flatten a tiny bit with the back of a spoon because these cookies don’t spread a whole lot. Bake for about 10 minutes in a preheated 375 degree oven.