In a skillet over medium heat, melt 1 tbsp butter and sauté the chopped onions until soft.
Add the minced garlic and cook for another minute until fragrant.
Add the ground beef and cook until browned. Drain excess grease if necessary.
Stir in Worcestershire sauce, paprika, salt, and black pepper.
Pour in beef broth and heavy cream. Simmer for 5 minutes until the mixture thickens.
Reduce heat and stir in shredded cheddar and mozzarella until melted and creamy.
Toast the bread slices in a separate pan with the remaining butter until golden brown.
Spoon the cheesy ground beef mixture over the toasted bread and serve hot.