1 (7-oz.) jar marshmallow crème
1-1/2 c. superfine sugar (Dominos confectioner's sugar)
1/4 c. unsalted butter
2/3 c. evaporated milk
12-oz pkg. semi-sweet chocolate chips
1 tsp. vanilla extract
Combine marshmallow crème, sugar, milk, and butter in 2-quart saucepan. Bring to a full, all-over boil, stirring constantly. Continue to boil on moderate heat, stirring constantly for 5 minutes. Remove from heat. Stir in chocolate chips and vanilla extract. Continue stirring until chocolate has completely melted. Pour into buttered 8-inch square dish. Cut into squares when cool. Top each square with 1 walnut half.