Caramelize the onions

• Melt the butter in a Dutch oven over medium heat.
• Add the sliced onions with a pinch of salt and cook, stirring occasionally, until deeply golden and jammy.

Add the garlic and thyme

• Stir in the minced garlic and thyme leaves and cook until fragrant.

Cook the pasta in the broth

• Pour in the beef broth and bring to a boil.
• Add the macaroni and simmer, stirring often, until al dente and most of the liquid is absorbed.

Make it creamy

• Lower the heat and stir in the heavy cream, Worcestershire sauce and Dijon mustard.
• Season with salt and pepper.

Melt in the cheese

• Take the pot off the heat and stir in the gruyère, mozzarella and parmesan until fully melted and glossy.

Serve

• Spoon into bowls and top with extra parmesan, black pepper and thyme.