In a large pot combine the butter, evaporated milk, and sugar. Cook over high heat, stirring continuously until the mixture reaches 234 degrees (use a candy thermometer to keep track of the temperature).

Remove from heat.

Stir in chocolate chips until they are completely melted and completely mixed in.

Add vanilla; stir well.

Stir in marshmallow cream until it is completely mixed with the chocolate.

Pour fudge into a greased pan or serving dish.

I put it in the refrigerator to cool it quickly. It will take approximately 4 -5 hours to cool if you leave it at room temperature which is way too long for my family to wait.