Preheat your oven to 350°F (175°C); line a 9x5-inch loaf pan with aluminum foil.

In a pot, heat olive oil; add onions and baking soda, cook for 15 mins, then reduce heat and cook for another 10-15 mins until golden brown.

Mix breadcrumbs with milk in a bowl; add most caramelized onions, garlic, Worcestershire sauce, salt, and pepper.

Add ground beef and beaten eggs; gently combine and transfer to the loaf pan, pressing down evenly.

Bake for 55-60 minutes until internal temp reaches 165°F (74°C).

Broil topped with reserved onions and Gruyère cheese for about 2 minutes until cheese is melted.

Let cool for 15 minutes, then slice and serve warm.