French Onion Soup Mac and Cheese

In a large skillet over medium-low heat, melt 4 tbsp of butter. Add the sliced onions and a pinch of salt. Cook slowly, stirring occasionally, for 20-30 minutes until deeply caramelized and sweet.

Stir in the dried thyme, then pour in the beef broth. Scrape up any browned bits from the bottom of the pan and cook until the liquid has mostly reduced. Set the onions aside.

To make the croutons, slice the baguette into 1-inch pieces. In a bowl, toss the bread with olive oil, salt, pepper, and optional fresh thyme leaves. Spread on a baking sheet and bake at 375°F (190°C) for 10-15 minutes, or until golden and crisp.

Bring a large pot of salted water to a boil. Cook the pasta according to package directions until al dente. Drain and set aside.

While the pasta cooks, make the cheese sauce. In a large pot or Dutch oven, melt the remaining 4 tbsp of butter over medium heat. Whisk in the flour and cook for 1 minute to form a roux.

Gradually whisk in the warm milk until the sauce is smooth and thickened. Bring to a simmer and cook for 2-3 minutes.

Remove the sauce from the heat. Stir in the Dijon mustard, nutmeg, and 8 oz of the shredded Gruyère cheese. Stir until the cheese is completely melted and the sauce is smooth.

Add the drained pasta to the cheese sauce along with half of the caramelized onions. Stir everything together until well combined.

Transfer the mac and cheese to a baking dish (or use an oven-safe skillet). Top with the remaining caramelized onions.

Briefly pulse the toasted baguette pieces in a blender or crush them by hand to create coarse breadcrumbs. Sprinkle the croutons and the remaining 2 oz of Gruyère cheese over the top.

Place under the broiler for 2-4 minutes, watching carefully, until the top is golden brown and bubbly. Let it rest for a few minutes before serving.