Creamy, Cheesy, Golden & Full of French Onion Flavor!
This French Onion Broccoli & Cheese Casserole is the ultimate comfort-food side dish. Tender broccoli is combined with sweet caramelized onions, creamy homemade cheese sauce, nutty Gruyère, sharp cheddar, and a buttery crispy topping. Every bite is rich, savory, cheesy, and incredibly satisfying.
Perfect for family dinners, Thanksgiving, Christmas gatherings, potlucks, or a delicious weeknight meal. No canned soup needed!
Recipe Information
– Prep Time: 20 minutes
– Cook Time: 35 minutes
– Total Time: 55 minutes
– Servings: 8
– Course: Side Dish
– Cuisine: American
– Cooking Method: Oven-Baked
Ingredients
For the Casserole
– 1 tablespoon olive oil
– 4 tablespoons unsalted butter, divided
– 2 large yellow onions, thinly sliced
– ½ teaspoon granulated sugar
– 1 teaspoon kosher salt, divided
– 2 garlic cloves, minced
– ½ teaspoon dried thyme
– 2 tablespoons all-purpose flour
– 1 cup low-sodium beef broth
– 1 cup whole milk
– 4 cups fresh broccoli florets
– 6 ounces Gruyère cheese, shredded
– 1 cup sharp cheddar cheese, shredded and divided
– ½ teaspoon ground black pepper
For the Crispy Topping
– 1 cup panko breadcrumbs
– 2 tablespoons unsalted butter, melted
– 1 tablespoon fresh parsley, chopped (optional)
Instructions
Step 1: Prepare the Oven
Preheat your oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish with butter or cooking spray.
Step 2: Caramelize the Onions
Heat olive oil and 2 tablespoons of butter in a large skillet over medium-low heat. Add the thinly sliced onions, ½ teaspoon salt, and granulated sugar.
Cook for 20–25 minutes, stirring occasionally, until the onions become soft, deeply golden, sweet, and caramelized.
Add minced garlic and dried thyme. Cook for another minute until fragrant. Remove from heat.
Step 3: Prepare the Broccoli
Bring a large pot of salted water to a boil. Add broccoli florets and blanch for approximately 2 minutes until bright green and crisp-tender.
Drain immediately and pat dry with paper towels. Removing excess water helps prevent a watery casserole.
Step 4: Make the Creamy Cheese Sauce
In a saucepan, melt the remaining 2 tablespoons of butter over medium heat.
Whisk in the flour and cook for approximately 1 minute. Slowly pour in the beef broth while whisking continuously.
Add the whole milk and simmer for 3–4 minutes until the sauce thickens.
Step 5: Add the Cheese
Remove the saucepan from the heat. Stir in the shredded Gruyère cheese and half of the cheddar cheese.
Mix until the cheeses melt and the sauce becomes smooth and creamy.
Add the remaining ½ teaspoon salt and black pepper. Adjust seasoning to taste.
Step 6: Combine Everything
Place the blanched broccoli and caramelized onions into the prepared baking dish.
Pour the creamy cheese sauce over the vegetables. Gently toss until everything is evenly coated.
Sprinkle the remaining cheddar cheese over the top.
Step 7: Prepare the Crispy Topping
In a small bowl, combine panko breadcrumbs with melted butter and chopped parsley.
Mix until the breadcrumbs are lightly coated. Sprinkle evenly over the casserole.
Step 8: Bake
Place the casserole in the preheated oven and bake uncovered for 18–22 minutes, or until the cheese sauce is bubbling and the breadcrumb topping is golden brown.
Step 9: Rest and Serve
Remove from the oven and allow the casserole to rest for 5–10 minutes before serving.
Garnish with fresh parsley or thyme if desired. Serve warm and enjoy!
Nutritional Information
Estimated per serving, based on 8 servings. Actual values vary by brand and ingredient substitutions.
Nutrient Amount
Calories 320 kcal
Protein 15 g
Total Carbohydrates 19 g
Dietary Fiber 3 g
Net Carbs 16 g
Total Fat 21 g
Saturated Fat 12 g
Sugar 5 g
Sodium 550 mg
Nut Information & Allergens
Tree Nuts: No tree nuts are included in the standard recipe.
Peanuts: No peanuts are included in the standard ingredients.
Almonds: Not included.
Walnuts: Not included.
Cashews: Not included.
Pecans: Not included.
Pistachios: Not included.
Other Allergens:
– Dairy: Contains butter, milk, Gruyère, and cheddar cheese.
– Gluten: Contains wheat flour and panko breadcrumbs.
– Soy: May be present in some packaged broth or breadcrumbs.
– Eggs: Not included in the standard ingredients, but check packaged product labels.
Nut Allergy Warning: This recipe does not require nuts. However, always check ingredient labels for cross-contamination warnings, especially for packaged breadcrumbs, broth, and shredded cheese.
Frequently Asked Questions (Q&A)
Q1: Can I use frozen broccoli instead of fresh broccoli?
Yes! Frozen broccoli works perfectly. Thaw it completely, drain thoroughly, and remove excess moisture before mixing it with the cheese sauce.
Q2: Can I prepare this casserole ahead of time?
Absolutely! Assemble the casserole without the breadcrumb topping, cover tightly, and refrigerate for up to 24 hours. Add the topping just before baking.
Q3: Can I use a different cheese instead of Gruyère?
Yes! Swiss, Jarlsberg, Fontina, or provolone are excellent alternatives. They melt beautifully and provide a delicious creamy texture.
Q4: Can I make this casserole without beef broth?
Yes. Vegetable broth works wonderfully. It is also a good option if you want to keep the casserole vegetarian.
Q5: How do I prevent my casserole from becoming watery?
Blanch the broccoli briefly and drain it thoroughly. Pat it dry before adding it to the sauce. Avoid overcooking the broccoli.
Q6: Can I use French-fried onions instead of panko breadcrumbs?
Yes! Crispy French-fried onions make a wonderful topping and add extra French onion flavor. Add them before baking, or during the final few minutes for extra crunch.
Q7: Can I make this recipe gluten-free?
Yes. Use gluten-free all-purpose flour, gluten-free panko breadcrumbs, and certified gluten-free broth and seasonings. Check the fried onion topping if using it.
Q8: How do I store leftovers?
Transfer leftovers into an airtight container and refrigerate for up to 4 days.
Q9: Can I freeze this casserole?
Yes! Assemble the casserole without the topping, wrap it tightly, and freeze for up to 2 months. Thaw overnight in the refrigerator before adding the topping and baking.
Q10: What is the best way to reheat this casserole?
Reheat in an oven at 325°F (165°C), covered, for 15–20 minutes. Remove the cover during the last 5 minutes to help crisp the topping.
Q11: Can I add chicken to this casserole?
Definitely! Add cooked shredded chicken or diced rotisserie chicken to make it a more filling main dish.
Q12: Is this casserole vegetarian?
It can be! Simply use vegetable broth instead of beef broth and make sure your cheese and other ingredients are suitable for a vegetarian diet.
Q13: What dishes go well with French Onion Broccoli & Cheese Casserole?
It pairs beautifully with roasted chicken, grilled steak, baked salmon, turkey, pork chops, or a fresh green salad.
Q14: Can I make this casserole without wine?
Yes. The recipe card does not require wine. Beef broth provides plenty of savory flavor.
Q15: How do I get a perfectly golden, crispy topping?
Mix the panko breadcrumbs with melted butter before sprinkling them over the casserole. Bake uncovered until golden. Watch carefully to prevent burning.
Helpful Recipe Tips
– Caramelize onions slowly for the best sweet and savory flavor.
– Freshly grate your cheese for a smoother, creamier sauce.
– Do not overcook the broccoli before baking.
– Use low-sodium broth to control the salt level.
– Add crispy fried onions for an extra crunchy topping.
– Allow the casserole to rest before serving so the sauce can set.
– Taste the cheese sauce before adding extra salt.