1 (16 ounce) can whole milk ricotta cheese
2 (3 ounce) packages cream cheese, softened
1/4 cup chopped onion
1 package (12 ounce) package shredded mozzarella cheese
1/2 pound sharp processed cheese food, at room temperature
2 tablespoons grated Parmesan cheese
Place ricotta cheese in a medium saucepan; cover and simmer over medium heat until warmed.
Stir cream cheese and onion into ricotta cheese mixture almost until blended. Mix in mozzarella cheese.
Return mixture to a medium saucepan over medium heat. Stir in Parmesan cheese. Cover, reduce heat to low, and simmer about 15 minutes.