How to Make Heavy Cream with Milk and Butter

the perfect christmas cinnamon roll 💌 recipe: (about 12-15 rolls) - 1 cup warm milk - 2 1/4 tsp instant yeast - 1 large egg - 1 tbsp melted butter - 4 tbsp white sugar - pinch of salt - 3 cups all purpose flour (plus extra to roll the dough) - heavy cream (goes on right before baking) filling: - 6 tbsp softened butter - 1/4 cup packed brown sugar - about a cup of mini marshmallows - 1/2 cup of mini chocolate chips (any kind) - 1.5 tbsp cinnamon icing: - 4 tbsp softened butter - 4 tbsp softened