Line a 9×13 pan with waxed paper.

In a large heavy saucepan melt the chocolate chips with the condensed milk over medium heat and beat with a wooden spoon until smooth.

Remove from heat and stir in the vanilla extract.

Stir in your walnuts and marshmallows, and pour the mixture into the prepared pan.

Let cool on counter, then chill for 1-2 hours.

Pop out the fudge using the waxed paper to help you. (You can dip the bottom of the pan in warm water for a couple of minutes if it needs help coming out.)

Peel off the waxed paper and cut in to cubes.