Preheat the oven to 350 degrees F. Line 2 baking sheets with parchment paper and set aside.
In a large stand mixer, cream together the butter and sugar for 2-3 minutes.
Add in the egg and vanilla and mix until well combined. Be sure to scrape down the sides of the bowl.
Add the peanut butter and mix.
Add the flour, baking soda and salt and mix until the flour is just combined.
Remove the bowl from the stand mixer and fold in the oats.
Using a medium sized cookie scoop, scoop 12 cookies onto each baking sheet. Bake for 12 minutes and then remove from the oven. If you don't want a chewy center, bake the cookies for about 13 - 14 minutes. Once the cookies are removed from the oven, let them sit on the baking sheet for a few more minutes before transferring them to a cooling rack.
Repeat the process with any remaining dough and store the cookies in an air tight container.
Drizzle with melted chocolate if needed.