French Onion Rigatoni Bake with Gruyère in One Skillet

Caramelized onions turn sweet and jammy in a cast iron skillet, then rigatoni simmers in that savory broth until nearly tender. A thick layer of grated Gruyère goes on top and the whole pan bakes until the cheese bubbles and browns into a blistered crust.

It is a one-pan dinner that goes from stovetop to table in about an hour, and every spoonful pulls stretchy cheese from the center.

This French onion rigatoni bake takes the best part of a classic French onion soup and turns it into a baked pasta you can make in a single skillet. The onions are cooked slowly in butter and olive oil until they are deep golden and sweet, then whole garlic cloves and fresh thyme go in, followed by beef broth to create a savory base.

Rigatoni goes right into that liquid and simmers until nearly tender, so the pasta absorbs the flavor as it cooks. Finally, a generous blanket of freshly grated Gruyère covers the top, and a short stint in a hot oven melts it into a golden, blistered crust.

Because everything happens in one pan, there is less washing up and the dish stays hot straight from the oven to the table.

Ingredients

Why this recipe works

The onions do most of the flavor work. Cooking them slowly over medium heat breaks down their natural sugars until they turn deep golden and jammy, and that sweetness carries through the whole dish. Scraping the browned bits from the pan into the broth adds another layer of savory depth, which is why the sauce tastes like French onion soup without any separate stock preparation.

Cooking the rigatoni directly in the seasoned broth is the second key. The pasta releases starch as it simmers, which thickens the liquid into a light, clinging sauce, and each piece absorbs the onion and thyme flavor from the inside out. Stopping the simmer while the pasta is still nearly tender means it finishes softening in the oven without turning mushy.

Notes and substitutions

Gruyère is the classic choice because it melts smoothly, stretches well and has a nutty, slightly salty flavor that suits caramelized onions. Buy a block and grate it yourself on a box grater, since pre-shredded cheese often contains anti-caking agents that keep it from melting as evenly. A fine, fluffy grate spreads easily over the pasta and browns into a thin, crisp crust.

A 12-inch cast iron skillet is ideal because it holds heat evenly for browning the onions and moves from stovetop to oven without a transfer.

You need a lid or a sheet of foil to cover the pasta while it simmers, and a wooden spoon helps scrape the bottom of the pan. Use low-sodium broth so you can control the saltiness, and taste before adding more kosher salt at the end of the onion stage.

• Gruyère cheese: Comté or a sharp aged white cheddar, grated just as finely
• low-sodium beef broth: Low-sodium vegetable broth, which gives a lighter, sweeter base
• dry rigatoni pasta: Penne or campanelle, which hold the onions and cheese well

Equipment

• 12-inch cast iron skillet with lid or foil
• Wooden cutting board
• Chef's knife
• Box grater
• Wooden spoon
• Measuring cups and spoons