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A bubbling broccoli casserole with a golden-brown crust fresh from the oven.

Spicy Lemon-Garlic Parmesan Broccoli Casserole

This spicy lemon-garlic Parmesan broccoli casserole features tender-crisp broccoli in a rich, creamy cheese sauce with a zesty Panko topping, perfect as a flavorful side or a light main course.
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Prep Time 20 minutes
Cook Time 40 minutes
Total Time 1 hour
Servings 6 people
Calories 450 kcal

Equipment

  • Large skillet
  • 9x13 inch baking dish
  • Small bowl
  • Whisk

Ingredients
  

Main

  • 1.5 lbs fresh broccoli cut into bite-sized florets
  • 1 tbsp butter
  • 0.5 chopped yellow onion
  • 4-5 cloves garlic minced
  • 1-2 tsp red pepper flakes
  • 1 zest of lemon
  • 1 juice of lemon juice after baking
  • 1 cup milk or half-and-half
  • 2 tbsp all-purpose flour
  • 1.5 cups shredded Parmesan cheese divided
  • Salt and black pepper to taste

Topping

  • 1 cup Panko breadcrumbs
  • 2 tbsp melted butter for topping

Instructions
 

Prepare Broccoli

  • Wash and cut the broccoli into florets, then blanch or steam until tender-crisp for 3-5 minutes. Drain thoroughly, squeezing out any excess water.

Sauté Aromatics

  • In a large skillet, melt 1 tablespoon of butter over medium heat and cook the chopped onions for 5-7 minutes until softened. Stir in the minced garlic and red pepper flakes and cook for another minute until fragrant.

Prepare Homemade Cheese Sauce

  • Whisk 2 tablespoons of flour into the same skillet to create a roux, cooking for 1-2 minutes. Gradually whisk in the milk until smooth and thickened, then stir in 1 cup of shredded Parmesan cheese until melted and creamy. Season with salt and black pepper to taste, then stir in the lemon zest.

Combine

  • Add the blanched and drained broccoli and sautéed aromatics to the creamy cheese sauce. Gently fold everything together until the broccoli is evenly coated.

Transfer to Baking Dish

  • Pour the broccoli mixture into a prepared 9x13 inch baking dish, spreading it out evenly.

Add Topping

  • In a small bowl, combine the Panko breadcrumbs with 2 tablespoons of melted butter and the remaining 1/2 cup of Parmesan cheese. Sprinkle this mixture evenly over the casserole.

Bake

  • Preheat your oven to 350°F (175°C) and bake for 25-35 minutes, or until bubbly and golden brown. If the topping browns too quickly, loosely tent with foil.

Rest and Serve

  • Allow the casserole to rest for 5-10 minutes after removing it from the oven. Just before serving, squeeze fresh lemon juice over the top, then scoop generously and enjoy!

Notes

For extra crispiness, you can broil the casserole for the last minute or two, watching carefully to prevent burning. Feel free to adjust the amount of red pepper flakes to your preferred spice level.