How do you make fondue & cream sauce not separate into oil?

How do you make a mushroom cream sauce, or chocolate fondue, with heavy cream, but in a way that the cream doesn't separate into solids and oil?How do you make fondue %26amp; cream sauce not separate into oil?
CHOCOLATE FONDUE OR ICE CREAM SAUCE



1 c. Milnot

1/2 c. butter

2 env. Choco-bake (premelted chocolate)

10 lg. marshmallows

1 tsp. vanilla

1 1/2 c. sugar

1/4 tsp. butter salt



Microwave: Combine milk, sugar, butter salt and chocolate in 4 cup measure. Cook, uncovered 6 minutes, stirring, occasionally and watching carefully last couple of minutes to avoid boiling over. Stir in marshmallows and cook 30 seconds; stir until marshmallows are melted.

Makes 3 cups sauce.



Tip: Square of unsweetened chocolate can be used instead of premelted. Just stir more often during first couple minutes to melt and distribute the chocolate. Use electric mixer helps.