Petite French Onion Mac + Cheese Recipe

Heat a large sauté pan over medium heat. Add 1 tablespoon olive oil and 2 tablespoons butter. Once the butter foams, add the thinly sliced onions and stir to coat.

Season onions with 1/2 tsp salt and 1/2 tsp granulated sugar (the sugar helps with browning). Cook, stirring every 2–3 minutes, until onions are soft and beginning to brown, about 15–20 minutes.

Reduce heat to medium-low. Add 120 ml vegetable stock and 1 tsp fresh thyme leaves. Continue to cook, stirring occasionally, until the liquid is mostly evaporated and onions are deeply golden and jammy, about another 10–12 minutes. Remove from heat and set aside.

Bring 2 liters of water to a rolling boil in a large pot. Add 1 tablespoon salt.

Add 340 g casarecce and cook until al dente according to package instructions (usually 8–10 minutes). Reserve 120 ml (about 1/2 cup) of the pasta cooking water, then drain the pasta.

Return drained pasta to the pot off the heat and toss with a splash of reserved cooking water to keep from sticking while you make the sauce.

Make the roux

In a medium saucepan over medium heat, melt 3 tablespoons butter. Sprinkle in 3 tablespoons flour and whisk continuously for 1–2 minutes to cook the raw flour taste but not brown the roux.

Add liquids

Gradually whisk in 500 ml whole milk until smooth. Then whisk in 120 ml vegetable stock. Bring mixture to a gentle simmer, whisking frequently, until it begins to thicken, about 4–6 minutes.

Season and finish

Stir in 1/2 tsp Dijon mustard, 1/2 tsp salt, 1/2 tsp freshly ground black pepper, and a 1/4 tsp pinch of grated nutmeg. Lower heat to low and remove pan from direct heat.

Add cheeses

Whisk in 200 g grated Gruyère a handful at a time until fully melted and smooth, then whisk in 40 g grated Parmesan. If sauce is too thick, whisk in up to 2–4 tablespoons of reserved pasta water to loosen to a creamy, pourable consistency.

Preheat oven to 200°C (400°F). Butter a small gratin dish or 9x9-inch baking dish (or individual oven-safe ramekins for 'petite' portions).

Combine the cooked casarecce, most of the caramelized onions (reserve 2 tablespoons for garnish), and the Mornay sauce in the pot or a large mixing bowl. Stir gently to coat pasta evenly. Taste and adjust seasoning with black pepper and a pinch more salt if needed.

Transfer pasta mixture to the prepared baking dish. Sprinkle 50 g extra grated Gruyère over the top. In a small bowl, combine 1/2 cup panko (if using) with 1 tsp olive oil and 1 tsp herbes de Provence; scatter over the cheese for a crisp topping. Alternatively, simply sprinkle herbes de Provence and remaining caramelized onions on top for a softer finish.

Bake uncovered until topping is golden and sauce is bubbling, about 12–15 minutes. For a browned, blistered top, place under a broiler for 1–2 minutes—watch closely to avoid burning.

Remove from oven and let rest 5 minutes. Garnish with reserved caramelized onions and fresh thyme sprigs. Season with black pepper to taste and serve immediately.