Combine graham cracker crumbs, peanuts, powdered sugar, and peanut butter with a pastry blender.
In a small saucepan, melt the chocolate chips and milk over low heat, stirring constantly until smooth.
Remove from heat and add vanilla.
Remove 1/2 cup and set aside.
Pour remaining chocolate mixture over crumb mixture and stir until well blended.
Spread evenly in a greased 9 inch square baking pan.
Frost with the reserved chocolate mixture.
Chill for about 1 hour.