Step 1: Prepare the Onions

1. In a large skillet, heat butter and olive oil over medium heat.
2. Add sliced onions and a pinch of salt, stirring occasionally. Cook for 20–25 minutes until the onions are golden brown and caramelized.
3. During the last 2 minutes, add the minced garlic and stir well. Remove from heat and allow to cool slightly.

Step 2: Mix the Meatloaf Base

1. In a large mixing bowl, combine ground beef, eggs, breadcrumbs, Worcestershire sauce, dried thyme, half of the caramelized onions, and a dash of salt and pepper.
2. Gently mix until combined. Avoid overmixing to maintain a tender texture.

Step 3: Shape the Meatloaf

1. Preheat your oven to 375°F (190°C).
2. Spoon the meat mixture into a loaf pan or shape it on a parchment-lined baking sheet. Smooth the top for even baking.

Step 4: Bake the Meatloaf

1. Place the meatloaf in the oven and bake for 45 minutes.
2. While it bakes, prepare the onion gravy.

Step 5: Prepare the Onion Gravy

1. Return the remaining caramelized onions to the skillet.
2. Add the beef broth, stirring to deglaze the pan and lift any browned bits.
3. Simmer for 5–7 minutes until the sauce thickens slightly. Remove from heat.

Step 6: Add the Cheese

1. Remove the meatloaf from the oven and sprinkle grated Gruyère cheese on top.
2. Return to the oven and bake for an additional 10–15 minutes, or until the cheese is melted and bubbly.
3. Ensure the internal temperature of the meatloaf reaches 160°F (71°C).

Step 7: Rest and Serve

1. Let the meatloaf rest for 5–10 minutes after removing it from the oven.
2. Slice and serve with the onion gravy drizzled over the top.