Baked Caramelized Onion & Mushroom Mozzarella Marinara Pasta

This Baked Caramelized Onion & Mushroom Mozzarella Marinara Pasta is what happens when you refuse to take a shortcut on the onions. Low and slow in butter and olive oil until they’re jammy, golden, and almost melting — then piled into a saucy Rao’s marinara penne with earthy cremini mushrooms and buried under a ridiculous amount of mozzarella and Parmesan. It bakes up bubbling and golden on top, saucy and rich underneath. Weeknight dinner, dinner party, “I need something comforting tonight” — this one covers all of it.

Why This is Delish

When you take the time to properly caramelize them — and we’re talking a real 20–25 minutes, not a rushed 5 — they turn almost jammy and sweet that completely transforms the marinara. Pair that with meaty cremini mushrooms, garlic, and Rao’s, and the sauce gets this deep, layered flavor that tastes way more complex than the ingredient list suggests. The triple cheese situation on top — shredded mozzarella, fresh sliced mozzarella, and Parmesan — means you’re getting crispy edges, gooey pulls, and a salty bite all at once.

How to Make Baked Caramelized Onion & Mushroom Mozzarella Marinara Pasta

Preheat oven to 400°F.

In a large skillet, heat olive oil and butter over medium heat. Add sliced onions with a pinch of salt and cook, stirring occasionally, for 20–25 minutes until deeply golden and caramelized. Set aside.

Add mushrooms and cook for 8–10 minutes until browned and softened. Stir in garlic, salt, and pepper, and cook for another minute until fragrant. Set aside.

Bring a large pot of salted water to a boil. Cook pasta until just shy of al dente. Reserve ¼ cup of pasta water, then strain the pasta.

Return the strained pasta to the same pot over low heat. Add the jar of Rao’s marinara sauce and the reserved pasta water.

Add the caramelized onion and mushroom mixture directly into the pot with the pasta and sauce. Mix until everything is fully combined and coated.

Transfer to a greased baking dish. Top with shredded, sliced, and grated mozzarella and parmesan.

Bake for 15–20 minutes, until the cheese is melted, bubbling, and lightly golden. Let it sit for 5 minutes, then finish with fresh basil, salt and pepper. Serve and enjoy!

Variations That Spice Baked Caramelized Onion & Mushroom Mozzarella Marinara Pasta Up

• Add Italian sausage or ground beef to the sauce for a heartier, meaty version.
• Stir in a handful of wilted spinach or roasted red peppers for extra color and flavor.
• Add a pinch of red pepper flakes or a drizzle of hot honey on top for a sweet heat moment.

Substitutions For Your Dietary Needs

• Swap regular pasta for your favorite gluten-free penne to make this gluten-free.
• Use dairy-free mozzarella and skip the Parmesan or use a vegan alternative to make it dairy-free.
• Any jarred marinara you love works here — Rao’s is the gold standard, but use what you have.

Recipe Hacks & Tips

• Don’t rush the onions — 20–25 minutes of patience is what makes this dish
• Pull the pasta before it’s fully al dente so it doesn’t overcook in the oven
• Use both shredded and sliced mozzarella for the best melt and those beautiful cheese pulls
• Let it rest for 5 minutes before serving so the sauce settles and the cheese sets slightly

Serve These Delicious Dishes

• Spicy Vodka Pasta
• Caramelized Onion Pasta
• Creamy Miso Pasta

How to Store Leftovers

Store leftovers in an airtight container in the fridge for up to 4 days. Reheat in the oven at 350°F covered with foil until warmed through, or microwave individual portions with a splash of water or marinara to keep it saucy. The flavors actually deepen overnight, making this an excellent next-day lunch.

Common Questions

Baked Caramelized Onion & Mushroom Mozzarella Marinara Pasta

A cozy, crowd-pleasing baked pasta with deeply caramelized onions, savory mushrooms, Rao's marinara, and three kinds of melty cheese. Perfect for weeknights or feeding a crowd.

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Yields: 6 Servings

Ingredients

• 1 Pound Rao’s Penne Rigate Pasta
• 2 Tablespoons Olive Oil divided
• 2 Tablespoons Butter divided
• 2 Large Yellow Onions thinly sliced
• 10 Ounces Cremini Mushrooms sliced
• 2 Cloves Garlic minced
• Salt & Pepper
• 1 Jar Rao’s Marinara Sauce
• 1 Cup Shredded Mozzarella Cheese
• 1 Mozzarella Ball sliced
• ½ Cup Grated Parmesan Cheese

Equipment

• Large Pot
• Large Skillet or sauté pan
• Wooden Spoon
• Colander
• 9×13-inch Baking Dish
• Microplane
• Grater

Instructions

• Preheat oven to 400°F.
• In a large skillet, heat olive oil and butter over medium heat. Add sliced onions with a pinch of salt and cook, stirring occasionally, for 20–25 minutes until deeply golden and caramelized. Set aside.
• Add mushrooms and cook for 8–10 minutes until browned and softened. Stir in garlic, salt, and pepper, and cook for another minute until fragrant. Set aside.
• Bring a large pot of salted water to a boil. Cook pasta until just shy of al dente. Reserve ¼ cup of pasta water, then strain the pasta.
• Return the strained pasta to the same pot over low heat. Add the jar of Rao’s marinara sauce and the reserved pasta water.
• Add the caramelized onion and mushroom mixture directly into the pot with the pasta and sauce. Mix until everything is fully combined and coated.
• Transfer to a greased baking dish. Top with shredded, sliced, and grated mozzarella, and parmesan.
• Bake for 15–20 minutes, until the cheese is melted, bubbling. Broil for 2-5 minutes until cheese is golden.
• Let it sit for 5 minutes, then finish with fresh basil, salt and pepper. Serve and enjoy!

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