Preheat oven to 350 degrees.  Grease or line a baking sheet with parchment paper.

Combine cake mix, butter, peanut butter,  egg, and vanilla in a large mixing bowl.  Mix until a cookie dough is formed.

Use a cookie scoop to drop cookie dough onto the baking sheet, one inch apart.

Press each cookie with a fork in a criss-cross pattern.

Bake for 10-12 minutes.

Let cookies cool for 5-10 minutes before moving them to a cooling rack.

Serve.