French Onion Rigatoni with Caramelized Vidalia Onions and Gruyere Step-by-step instructions

Before you start

Before starting, set a large pot of salted water to boil and prepare a box grater. Slice the onions into thin, uniform crescents and strip the thyme leaves. Grate the cheeses into a bowl and combine.

Have the cast iron skillet ready and the broiler preheated for later. The entire dish comes together in about 45 minutes, with most of that time spent caramelizing the onions.

Instructions

Prep and Pasta

1. 1Prep the Onions and Cheese
   Slice the Vidalia onions into uniform crescents, about 1/4-inch thick. Strip the leaves from the thyme sprigs and set aside. Grate the aged Gruyere and provolone on a box grater into a large bowl; toss to combine.
   Look for Onions are in thin, even crescents; cheese is a fluffy pile.
   Tip Grating your own cheese ensures it melts smoothly and evenly.
2. 2Cook the Rigatoni
   Bring a large pot of generously salted water to a boil. Add the rigatoni and cook until al dente according to package directions. Reserve 1 cup of pasta water, then drain the pasta.
   Look for Pasta is tender but still has a slight bite in the center.
   Tip Reserve more pasta water than you think you need; it helps loosen the sauce.

The onions are sliced into even crescents, the thyme is stripped, and the cheeses are grated and mixed.

The rigatoni is al dente, drained, and reserved with pasta water. The kitchen smells of fresh thyme and butter.

Caramelize and Sauce

3. 3Caramelize the Onions
   Melt the butter in a 12-inch cast iron skillet over medium heat. Add the sliced onions and a pinch of salt. Cook, stirring occasionally, until the onions are deeply caramelized and golden brown, about 20 minutes. Reduce heat if they begin to burn.
   Look for Onions are soft, deeply browned, and smell nutty and sweet.
   Tip Be patient; low and slow is key to even caramelization without burning.
4. 4Add Thyme and Cream
   Stir in the fresh thyme leaves and cook for 1 minute until fragrant. Pour in the heavy cream and bring to a gentle simmer. Cook for 2-3 minutes, stirring, until the cream slightly thickens.
   Look for The cream is bubbling gently and has turned a pale golden color.
   Tip Scrape the bottom of the skillet to incorporate the browned bits.
5. 5Combine Pasta and Sauce
   Add the drained rigatoni to the skillet. Toss well to coat every piece in the creamy onion sauce. If the sauce is too thick, add a splash of the reserved pasta water to loosen it.
   Look for Each rigatoni is glistening with sauce, and the skillet looks creamy.
   Tip The sauce will continue to thicken as it sits; keep it slightly looser than desired.

The onions are deeply golden, soft, and sweet, with browned bits sticking to the skillet. The cream has thickened slightly and is flecked with thyme. The pasta is coated in a creamy, pale golden sauce.

Cheese Crust and Broil

6. 6Top with Cheese
   Preheat the broiler. Sprinkle the shredded Gruyere and provolone mixture evenly over the top of the pasta, covering completely. You want a thick, craggy layer.
   Look for The cheese covers the entire surface in an even, thick layer.
   Tip A thick layer creates the blistered, golden crust you're after.
7. 7Broil Until Golden
   Place the skillet under the broiler for 2-4 minutes, until the cheese is melted, blistered, and golden brown in spots. Watch closely to prevent burning.
   Look for The cheese is bubbling and browned with dark spots; the edges are crisp.
   Tip Rotate the skillet halfway through for even browning.
8. 8Garnish and Serve
   Remove the skillet from the oven. Scatter fresh thyme leaves and cracked black pepper over the blistered Gruyere. Let sit for 3 minutes, then pull a crispy, cheese-stretching portion to serve.
   Look for The cheese pulls into long, stretchy ribbons; the top is crackly.
   Tip Letting it rest helps the cheese set slightly for cleaner servings.

The cheese is melted, bubbly, and blistered with dark golden spots. The top is crisp and crackly, while the interior is creamy and steamy. Fresh thyme and cracked pepper add a bright finish.

Common mistakes

One common mistake is rushing the onions; if the heat is too high, they will burn before they caramelize. Keep the heat at medium and stir occasionally, allowing them to soften and turn golden gradually.

Another pitfall is over-broiling the cheese; watch it closely, as it can go from golden to burnt in seconds. If the sauce seems too thick, loosen it with reserved pasta water before adding the cheese.

How to tell it’s done

The dish is done when the cheese is melted, blistered, and golden brown in spots, and the edges are crisp. The onions should be deeply caramelized and jammy, and the sauce should coat the pasta without being runny.

To check, lift a portion with a fork; the cheese should stretch and the pasta should be tender but firm to the bite.