Preheat oven to 375℉ and position oven rack to the centre. Line baking trays with parchment and set aside.
In a small bowl whisk together flour, baking soda and salt.
Using a stand mixer fitted with a paddle attachment or electric hand mixer, cream together butter and sugars until light. Add egg and beat until light and fluffy.
Add peanut butter and vanilla and beat on low until just combined. Stir in flour mixture on low speed to combine just until flour is absorbed, scraping bowl once. Add in chopped chocolate covered peanuts and mix on low until evenly distributed.
Using a 1 ounce scoop, scoop cookies onto prepared sheet, spacing at least 2" apart. Flatten cookies using your palm or bottom of a small cup dipped in flour to prevent sticking. Top each cookie with a whole chocolate covered peanut.
Bake for 10-11 minutes until golden. Remove pan and allow cookies to cool for 5 minutes on tray before moving to a cooling rack.
I prefer to bake one tray at a time, however if baking two trays, swap trays halfway through baking.