Caramelized Onion Casserole with Crispy Topping

This Caramelized Onion Casserole with Crispy Topping is a celebration of the humble onion, transformed into a luscious, golden masterpiece. Layers of sweet and savory caramelized onions are enveloped in a velvety sauce, topped with a crispy, golden crust. Every bite is a symphony of flavors and textures, making this casserole a standout dish for any occasion.


For the Caramelized Onions:

  • 4 large onions, thinly sliced
  • 2 tablespoons butter
  • 1 tablespoon olive oil
  • 1 teaspoon sugar
  • Salt and pepper, to taste

For the Casserole:

  • Caramelized onions (from above)
  • 3 cups cooked pasta (penne or rigatoni work well)
  • 1 cup Gruyere cheese, grated
  • 1 cup Parmesan cheese, grated
  • 1 cup mozzarella cheese, shredded
  • 2 cups milk
  • 3 tablespoons all-purpose flour
  • 3 tablespoons butter
  • 1/2 teaspoon nutmeg
  • Salt and pepper, to taste

For the Crispy Topping:

  • 1 cup breadcrumbs
  • 2 tablespoons butter, melted
  • 1/4 cup Parmesan cheese, grated


Step 1: Caramelize the Onions

  1. In a large skillet, heat 2 tablespoons of butter and 1 tablespoon of olive oil over medium heat.
  2. Add the thinly sliced onions and cook, stirring occasionally, until they become soft and golden brown. This process may take around 20-30 minutes.
  3. Sprinkle the sugar over the onions and continue cooking until they caramelize to a rich golden color. Season with salt and pepper. Set aside.

Step 2: Prepare the Pasta

  1. Cook the pasta according to the package instructions. Drain and set aside.

Step 3: Make the Cheese Sauce

  1. In a saucepan, melt 3 tablespoons of butter over medium heat.
  2. Add the flour and whisk continuously for 2-3 minutes to create a roux.
  3. Gradually whisk in the milk, ensuring there are no lumps.
  4. Continue whisking until the sauce thickens.
  5. Stir in the Gruyere, Parmesan, and mozzarella cheeses until melted and smooth.
  6. Season the sauce with nutmeg, salt, and pepper.

Step 4: Assemble the Casserole

  1. Preheat your oven to 375°F (190°C).
  2. In a large mixing bowl, combine the cooked pasta, caramelized onions, and the cheese sauce. Mix until well combined.
  3. Transfer the mixture to a greased casserole dish.

Step 5: Prepare the Crispy Topping

  1. In a small bowl, combine the breadcrumbs, melted butter, and grated Parmesan cheese.

Step 6: Add the Crispy Topping and Bake

  1. Sprinkle the crispy topping evenly over the pasta mixture.
  2. Bake in the preheated oven for 25-30 minutes or until the top is golden and the casserole is bubbly.

Step 7: Serve and Enjoy

  1. Allow the casserole to cool slightly before serving.
  2. Serve this luscious Caramelized Onion Casserole with Crispy Topping as a side dish or a comforting main course.


  • Experiment with different types of onions for varying flavors. Sweet onions add an extra layer of sweetness.
  • Feel free to customize the cheese blend based on your preferences. Fontina or Swiss cheese can also be excellent choices.
  • This casserole can be prepared ahead of time and baked just before serving.

This Caramelized Onion Casserole with Crispy Topping is a testament to the transformative power of simple ingredients. The sweet, golden onions combined with the creamy cheese sauce and crispy topping create a dish that is both comforting and sophisticated. It’s perfect for family dinners or when you want to impress with a side dish that steals the show.

Leave a Reply

Your email address will not be published. Required fields are marked *

Raspberry Dip

Homemade Pineapple Squares