Line a 9 x 13 pan with foil so it hangs over the edges of the pan.

In a large heavy pan, melt butter, sugar and milk together.

Cook over medium heat, stirring constantly, until it comes to a rolling boil.  Boil for 5 minutes.

Remove pan from heat and add in white chocolate chips, marshmallows, 1 cup of walnuts and maple flavoring.

Pour into lined pan. Top with remaining walnuts and gently press into fudge.

Refrigerate for 1 hour or allow to set up at room temperature.

Lift parchment paper to remove fudge from pan. Cut into squares. Makes 24 pieces.