Caramelize the onions

• Melt the butter in a large pan over medium-low heat.
• Add the sliced onions with a pinch of salt and cook slowly, stirring often, until deep golden and jammy.

Build the flavor base

• Add the minced garlic and dried Italian herbs and cook until fragrant.
• Pour in the white wine and scrape up the browned bits from the pan.
• Season with salt and pepper.

Cook the pasta in the broth

• Add the rigatoni and beef broth to the pan.
• Simmer, stirring occasionally, until the pasta is al dente and most of the liquid is absorbed.

Make it creamy

• Lower the heat and pour in the heavy cream.
• Stir in the grated parmigiano and gruyère until melted and silky.

Add the cheese pull and serve

• Scatter the mozzarella over the top, cover and let it melt.
• Season to taste and serve hot.