Caramelized Onion Pasta Casserole

This one-pan caramelized onion pasta transforms simple ingredients into a deeply flavorful comfort dish that's become my go-to for both weeknight dinners and casual entertaining. The slow-roasted onions develop an incredible sweetness that creates a naturally rich sauce without heavy cream or butter.

I first made this pasta during a particularly busy work week when I needed something that would practically cook itself. The aroma of the onions caramelizing filled my kitchen and instantly became a comfort signal that good food was on its way.

Ingredients

• Yellow onions: The star ingredient that transforms into sweet caramel goodness through slow roasting. Look for firm onions with dry papery skins
• Whole garlic head: Roasting mellows the flavor while intensifying its sweetness. Choose a plump head with tight cloves
• Sun dried tomatoes: Add concentrated umami flavor and beautiful color. Oil packed works best but dried ones rehydrated work too
• Coconut milk: Creates a luscious creamy sauce without dairy. Use full fat for best texture
• Farfalle pasta: The bow tie shape captures the sauce beautifully. Any short pasta works well
• Fresh herbs: Basil and parsley brighten the rich flavors. Use the freshest you can find for best flavor
• Lemon juice: Adds necessary acidity to balance the sweet onions. Choose a juicy fresh lemon

Step-by-Step Instructions

Prepare the casserole:

Combine sliced onions, sun dried tomatoes, and seasonings in a casserole dish. Place the whole garlic head with its top sliced off in the center, creating a flavor centerpiece. Drizzle everything generously with olive oil or the flavorful oil from sun dried tomatoes to ensure proper caramelization.

Slow roast:

Cover the dish with foil to create a steam environment that helps soften the onions before they caramelize. Roast at 400°F for a full hour, tossing halfway through to ensure even cooking. The onions will gradually transform from sharp and pungent to meltingly sweet and golden brown.

Cook the pasta:

About 20 minutes before the onions finish, cook your farfalle according to package directions. Be sure to salt the pasta water generously and cook to al dente. Remember to reserve some starchy pasta water before draining to help bind your sauce.

Create the sauce:

Once the onions and garlic are beautifully caramelized, carefully remove the garlic head. When cool enough to handle, squeeze the softened cloves into the onion mixture. Add coconut milk, fresh herbs, and lemon juice, then stir to create a silky sauce.

Combine and finish:

Add your cooked pasta directly to the casserole dish. Toss everything together, gradually adding reserved pasta water as needed to reach your desired sauce consistency. The starch in the water helps create a silky texture that clings perfectly to the pasta.

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The roasted garlic is perhaps my favorite component of this dish. The first time I served this to my Italian neighbor, she was amazed at how the garlic transformed from sharp and pungent to sweet and buttery through the roasting process. Now she makes it regularly for her family too.

Make Ahead Options

This pasta is actually even better the next day when the flavors have had time to meld together. You can prepare the entire dish up to two days ahead and reheat in a covered dish in a 350°F oven until warmed through. Add a splash of water or broth if it seems dry after refrigeration. For meal prep, you can also roast the onion mixture days ahead and freeze it, then simply thaw and combine with freshly cooked pasta when ready to serve.

Perfect Pairings

The sweet caramelized onions and tangy tomatoes in this pasta pair beautifully with crisp acidic whites like Pinot Grigio or Sauvignon Blanc. For a complete meal, serve with a peppery arugula salad dressed simply with lemon and olive oil to cut through the richness of the pasta. A side of roasted asparagus or broccolini also complements the flavors wonderfully.

Seasonal Adaptations

During summer months, add fresh cherry tomatoes in the last 15 minutes of roasting for bursts of garden freshness. In autumn, try incorporating a diced butternut squash to the roasting pan for added sweetness and texture. Winter calls for maybe adding some roasted mushrooms for earthy depth. Spring is perfect for garnishing with fresh peas and tender herbs just before serving.

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This dish is a simple yet elegant way to showcase the magic of caramelized onions and fresh ingredients. Perfect for weeknight ease or impressing dinner guests.

Frequently Asked Questions

→ Can I use a different type of pasta for this dish?

Yes, you can substitute the farfalle with any pasta shape you prefer. Penne, rigatoni, or fusilli would work well as they catch the sauce in their ridges and curves. Just be sure to cook according to package directions and reserve some pasta water as indicated in the recipe.

→ Is there a substitute for coconut milk?

If you don't enjoy coconut flavor or have allergies, you can substitute with regular cream, cashew cream, or even a dairy-free alternative like oat cream. Each will change the flavor profile slightly but will still provide the creamy texture needed for the sauce.

→ How can I tell when my onions are properly caramelized?

Properly caramelized onions should be deeply golden brown (not burnt), very soft, and significantly reduced in volume. They develop a sweet, rich flavor that's fundamental to this dish. The full hour of cooking time is important to achieve this transformation.

→ Can I make this dish ahead of time?

Yes, you can prepare the caramelized onion mixture ahead of time and refrigerate for up to 2 days. When ready to serve, cook the pasta fresh, then combine with the reheated onion mixture and remaining ingredients. You may need additional pasta water to loosen the sauce.

→ What can I serve with this pasta dish?

This pasta works wonderfully with a simple green salad with light vinaigrette to balance the richness. For a more substantial meal, serve with garlic bread or roasted vegetables. A glass of dry white wine makes an excellent accompaniment to the sweet caramelized flavors.

→ Is this dish vegan?

Yes, this pasta dish is completely plant-based. The creaminess comes from coconut milk rather than dairy products, and all other ingredients are plant-derived. It's an excellent option for those following a vegan diet but appealing to all eaters.