Preheat oven to 350 degrees. Prepare a baking sheet by lining with parchment paper or a Silpat liner. Set aside.

In a large mixing bowl, use a handheld mixer to blend the butter with both sugars until smooth.

Once completely incorporated, add the egg, vanilla, and peanut butter. Mix well to combine.

Next, add the flour, salt, and baking soda and just blend into the peanut butter mixture. Don't over mix the cookie dough. Stir in the oatmeal.

Using a medium-sized ice-cream scoop, which will allow for more even and uniform cookies, position mounds of the dough evenly on a cookie sheet. Be sure to leave room for growth.

Bake for 12 minutes. Allow the cookie to cool for two minutes on the baking sheet before transferring to a cooling rack for the remainder of the cooling process.