Combine flour, peanuts and sugar in the jar of a blender and blend until mealy-- peanuts should be ground fine but not turned to peanut butter. Pour in melted butter and blend just a few pulses until it comes together and turn into an ungreased 8x8 baking dish. Press into the bottom of the pan until even and bake at 350 degrees for about 10 minutes or until crust is light brown around the edges.
Microwave the chocolate chips with peanut butter in a microwaveable bowl for 30 seconds, stir and continue to cook in 30 second intervals until the chocolate is melted and mixture is smooth. Stir powdered sugar into chocolate and mix until smooth once more.
Spread chocolate evenly over hot cookie base and set aside until cooled. It will be ready to cut when the chocolate is no longer shiny. Cut into bars and serve at room temperature.