In a large skillet over medium heat, add the ground beef or turkey, breaking it apart as it cooks. Stir occasionally until browned, about 5-7 minutes.

Using the same skillet, add the finely chopped onion and minced garlic. Sauté them over medium heat for 3-4 minutes until the onion is translucent and fragrant.

Stir in the ketchup, Worcestershire sauce, brown sugar, smoked paprika, salt, and pepper, mixing everything well. Allow the mixture to simmer on low heat for 5-7 minutes until it thickens.

Preheat your oven to 375°F (190°C). Spread softened butter on one side of each thick-cut bread slice and arrange them buttered-side down on a baking sheet.

Spoon the savory meat mixture generously onto each slice of bread. Top with shredded mozzarella and grated Parmesan if desired.

Slide the baking sheet into the preheated oven and bake the melts for 10-12 minutes or until the cheese is bubbly and golden.

Let the melts cool for a few minutes. Garnish with fresh parsley if using, slice diagonally, and serve warm.