Have all your mix-in ingredients ready to go (oats, peanut butter, vanilla, and salt) so the mixture doesn’t begin to set up prematurely before you’ve have the chance to scoop them into balls.
You can make the cookies larger, but note that they can take a bit longer to set. We were able to get 36 teaspoon-sized cookies out of this recipe, and they only took 15 minutes to set. If you use a Tablespoon to scoop, allow them to set for 30-40 minutes.