In a skillet, heat a little olive oil over medium heat. Add the sliced onions and cook them until they are caramelized and golden brown, about 15–20 minutes. Stir frequently and set aside to cool slightly.
In a large mixing bowl, combine the ground beef, ground turkey, breadcrumbs, cooled caramelized onions, eggs, French onion soup, Worcestershire sauce, garlic powder, thyme, salt, and pepper. Mix well until all ingredients are fully incorporated.
Transfer the mixture to a lined or greased loaf pan and shape it into a loaf.
Sprinkle the grated Gruyère cheese evenly over the top of the meatloaf.
Place the meatloaf in the preheated oven and bake for 1 hour or until the internal temperature reaches 160°F (70°C).
Once cooked, take the meatloaf out of the oven and let it rest for 10 minutes before slicing. This helps keep it moist.
Serve warm, garnished with fresh parsley.
Notes
Serve on a rustic wooden platter with extra French onion soup for added flavor.