Crust: Preheat the oven to 350 ° F. Crush the cookies until they're fine crumbs. Pour the melted butter over the top and stir with a fork to combine. Press into individual tart shells and bake until set, 5 to 7 minutes. Remove from the oven and let it cool completely.
Filling: Beat the PBfit peanut butter blend with the cream cheese until smooth. Add the powdered sugar and beat until smooth. Add the thawed whipped topping and fold until smooth, scraping the sides as needed.
Pour the filling into the tart shells, evening out the top with a knife or spatula. Chill for at least an hour before serving. Garnish with melted chocolate and chopped peanuts if desired.