Preheat oven to 190ºC . Line 23 cm square pan with aluminum foil. Combine crumbs, sugar and margarine; press firmly on bottom of prepared pan. Bake 8 minutes. Cool.
In heavy saucepan, over low heat, melt chocolate chips with condensed milk and vanilla. Remove from heat; stir in cheese until well blended. Stir in nuts. Spread over prepared crust. Chill 2 hours or until firm. Lift fudge from pan onto cutting board; peel off foil and cut into squares. Store covered in refrigerator.