1 c. butter, melted
2 c. peanut butter
4 c. powdered sugar
1 c. brown sugar
1 tsp. vanilla
2 c. nuts, chopped (optional)
12 oz. chocolate chips, melted

I use chunky peanut butter, so I don't need to add nuts separately.

Mix peanut butter, powdered sugar, brown sugar and vanilla. Add butter; mix well. Add nuts. Pat out evenly on a big cookie sheet (15 x 10 inches or bigger). Spread melted chocolate over top. Cut immediately. Best when kept chilled.