1. In a large skillet, heat the olive oil over medium heat.

2. Add the thinly sliced yellow onions and sprinkle with sugar.

3. Cook the onions, stirring occasionally, until they become soft and golden, about 15-20 minutes.

4. Towards the end of the cooking time, sprinkle the onions with baking soda and cook for an additional minute.

5. Set the caramelized onions aside to be incorporated into the meatloaf mixture and the French onion sauce later.

6. Preheat your oven to 350°F.

7. In a large bowl, combine the ground beef, half of the Gruyere cheese, panko breadcrumbs, garlic, thyme, rosemary, salt, and pepper. Gently mix until just combined.

8. Form the meatloaf mixture into a loaf shape and place it in a greased baking dish.

9. Bake for 45-50 minutes, or until the internal temperature reaches 165°F.

10. While the meatloaf is baking, prepare the French onion sauce by melting butter in the same skillet used for the onions. Add beef broth, red wine, and Worcestershire sauce, then stir in reserved caramelized onions. Simmer for 5-7 minutes.

11. Once the meatloaf is cooked through, pour the French onion sauce over the top and layer with remaining Gruyere cheese slices.

12. Return to the oven for an additional 10-15 minutes, or until the cheese is melted and bubbly.

13. Serve hot with sliced baguette rounds.