1/2 c butter, softened
1/2 c sugar
1/2 c packed brown sugar
1/2 tsp vanilla
1 1/4 c flour
3/4 tsp baking soda
1/2 tsp salt
Cream butter and peanut butter and sugars, add egg and vanilla. Stir flour, soda and salt and add to creamed mixture. Mix well, chill 1 hour.
Shape into 1 inch balls and place into lightly greased mini muffin tin. Bake at 325 for 14 min. Remove and make wells in center, using a melon baller,spoon, or wooden utensil (used with mini muffin tins). Sometimes they will fall and make a natural well. Let cool in pan and remove to wire cooling rack.
In double boiler, melt 2 c chocolate chips, 1 (14oz) can sweetened condensed milk until smooth, stir in 1 tsp vanilla, spoon into centers of cookies and top with chopped peanuts.
Double boiler for melting chocolate
Left over filling is wonderful reheated and used for hot fudge topping with ice cream.
If you don't have a mini muffin tin, you can find them in most stores, if you can I recommend the silicone one over the traditional metal pan.