Reduce the heat to low and start adding the cheeses. Begin with 1 cup of shredded mozzarella, stirring until it melts and combines with the cream.
Next, add 1/2 cup of grated Parmesan and 1/4 cup of grated Romano. Stir continuously until the sauce is smooth, creamy, and well blended.
Season the sauce with 1/2 teaspoon salt and 1/4 teaspoon black pepper. Remember, the cheese adds saltiness, so taste before adding more.