Broccoli Cheese Quinoa Casserole
A wholesome, one-dish casserole combining fluffy quinoa and tender broccoli florets in a silky cheddar cheese sauce, topped with crispy buttered breadcrumbs. Baked until golden and bubbling, this is comfort food that's also nutritious. Perfect for weeknight dinners, potlucks, or casual entertaining—it comes together quickly and feeds a crowd.
- Prep
- 25 min
- Cook
- 45 min
- Wait
- 5 min
- Total
- 1 hr 15 min
- Makes
- Serves 6 (one 9×13-inch casserole)
Steps
Before you start
- Cook 1 cup uncooked quinoa per package directions, or use 3 cups store-bought pre-cooked quinoa, and let it cool
- Preheat oven to 375°F (190°C)
- Lightly butter a 9×13-inch (23×33 cm) baking dish
- Measure all ingredients and have them ready to use
Prepare Broccoli
- Wash the broccoli under cool running water.
- Cut each head into bite-sized florets, about 1½ to 2 inches each.
- Discard the tough lower stem portions, or if you prefer, trim them, peel away the woody exterior, and cut into small pieces for inclusion.
- You should have approximately 5 cups of florets.
+ Show details− Hide details
Ready when: Florets are uniform in size, about 1½ to 2 inches, and ready to combine
Tip: Keeping florets relatively uniform helps them cook evenly. Larger pieces may remain undercooked, while tiny pieces turn mushy.
Sauté Onion and Garlic
- Melt 2 tablespoons of butter in a medium saucepan over medium heat.
- Once foaming, add the diced onion and cook, stirring occasionally, for 3 minutes until the onion softens and becomes translucent.
- Add the minced garlic and cook for another minute, stirring constantly, until very fragrant.
+ Show details− Hide details
Ready when: Onion is soft and translucent; garlic is very fragrant and light golden
Tip: Watch the garlic carefully—if it browns, it will taste bitter. Stir constantly in the final minute.
Make Roux and Whisk in Milk
- Sprinkle the flour directly over the onion and garlic mixture.
- Stir constantly with a wooden spoon or whisk for about 1 minute, ensuring all the flour is fully incorporated and no dry bits remain.
- The mixture will resemble a thick paste.
- Remove the pan from heat briefly.
- Slowly pour in about ¼ cup of the milk while whisking constantly.
- Once that portion is incorporated and the mixture is smooth, gradually pour in the remaining milk while continuing to whisk to prevent lumps.
- Return the pan to medium heat.
+ Show details− Hide details
Ready when: Mixture is smooth, creamy, and free of lumps; will gradually begin to thicken as it heats
Tip: Add milk slowly and whisk continuously to avoid lumps. Starting with a small amount helps fully incorporate the roux before adding more liquid.
Thicken the Sauce
- Keep the sauce over medium heat, stirring frequently with a whisk or spoon, for 5 to 7 minutes.
- The sauce will gradually thicken and bubble gently.
- It's done when it coats the back of a spoon—dip the spoon in, remove it, and run your finger across the back of the spoon; it should leave a clear trail.
+ Show details− Hide details
Ready when: Sauce coats the back of a spoon with a thick layer; when you drag your finger across, it leaves a trail and the sauce doesn't immediately fill in the gap
Tip: Stir often to prevent the bottom from scorching. If the sauce is still too thin after 7 minutes, let it cook another 1 to 2 minutes, but don't let it come to a rolling boil.
Melt Cheese and Season
- Remove the saucepan from heat.
- Add the shredded cheddar cheese, salt, black pepper, and nutmeg.
- Stir gently for 1 to 2 minutes until the cheese is completely melted and the sauce is smooth, creamy, and a uniform golden color.
- Taste the sauce and adjust salt and pepper if needed.
- (If using eggs, lightly beat them in a small bowl now.)
+ Show details− Hide details
Ready when: Cheese is fully melted; sauce is smooth, creamy, unified in color, and pourable
Tip: Nutmeg adds warmth and subtle flavor without being obvious—start with ¼ teaspoon and taste. You can always add more, but you can't remove it.
Mix Casserole Base
- In a large mixing bowl, combine the cooked quinoa and prepared broccoli florets.
- Pour the cheese sauce over them and gently fold everything together using a rubber spatula or large spoon, until the broccoli and quinoa are evenly coated with sauce.
- If using beaten eggs, add them now and fold gently until just combined.
- Transfer the entire mixture to the prepared 9×13-inch baking dish, spreading it into an even layer.
+ Show details− Hide details
Ready when: All ingredients are evenly combined; mixture is transferred to the baking dish in an even layer
Tip: Fold gently rather than stirring vigorously—you want to keep the broccoli florets intact and not crush the quinoa grains.
Prepare Breadcrumb Topping
- In a small bowl, combine the panko breadcrumbs with 2 tablespoons of melted butter.
- Toss with a fork, stirring and pressing gently, until the breadcrumbs are evenly moistened and look slightly clumpy.
- Scatter and distribute this mixture evenly over the top of the casserole, covering as much surface as possible.
+ Show details− Hide details
Ready when: Breadcrumbs are evenly coated with butter and loosely scattered across the top of the casserole
Tip: The melted butter helps the breadcrumbs toast golden and become crispy. Evenly distributed toppings ensure consistent browning across the casserole.
Bake Until GoldenOven 375°F / 190°C
- Place the casserole in the preheated 375°F (190°C) oven on the middle rack.
- Bake for 30 to 35 minutes, until the breadcrumb topping is deep golden brown and the filling is heated through (you should see it bubbling gently at the edges).
- If the topping browns too quickly before the filling is hot, tent it loosely with aluminum foil for the last 10 minutes of baking.
+ Show details− Hide details
Ready when: Breadcrumb topping is deep golden brown; casserole is bubbling gently at the edges; cheese is steaming hot throughout
Tip: Don't overbake, or the broccoli will become mushy and the texture will suffer. Watch for the golden-brown topping and bubbling edges as your visual cues.
Rest and Serve
- Remove the casserole from the oven and let it sit at room temperature for 5 to 10 minutes before serving.
- This allows the cheese sauce to set slightly, making portions easier to scoop and serve without everything falling apart.
+ Show details− Hide details
Ready when: Casserole has cooled slightly and is easier to portion
Tip: If you prefer a more cohesive, firm casserole, let it rest for the full 10 minutes rather than 5.
Good to know
Tips
- Make sure your quinoa is fully cooked and cooled before mixing it into the casserole. Warm quinoa can break apart too easily when folded.
- The cheese sauce is the key to this dish—don't rush the roux or milk-whisking steps. A smooth, well-thickened sauce ensures a cohesive, creamy casserole.
- For extra richness and creaminess, use half whole milk and half heavy cream instead of all whole milk.
- This casserole is a great canvas for other vegetables: sauté mushrooms, spinach, diced bell peppers, or corn and fold them in without changing the baking time.
Make ahead
The casserole can be assembled up to 24 hours ahead and refrigerated, covered. Add 5 to 10 minutes to the baking time if baking from cold. Alternatively, the cheese sauce can be made up to 2 days ahead, cooled, covered, and refrigerated; reheat gently over low heat before combining with quinoa and broccoli.
Storage & reheating
Room temperature: Cover loosely and consume within 2 hours. Refrigerator: Cover with plastic wrap or foil after it cools; store up to 3 days. Reheat portions in the microwave at 50% power for 2 to 3 minutes, or in a preheated 325°F oven for 15 to 20 minutes covered with foil. Freezer: Cool completely, then transfer to a freezer-safe container or wrap well in foil and plastic wrap; store up to 3 months. Thaw overnight in the refrigerator before reheating in a 325°F oven for 30 to 40 minutes covered.
Substitutions
- sharp cheddar cheese, shredded → Gruyère, Emmental, or mild cheddar cheese. Gruyère and Emmental will provide a nuttier, more sophisticated flavor; mild cheddar will taste less sharp and bold.
- broccoli florets, fresh → Cauliflower florets, or a mix of broccoli and cauliflower. Cauliflower has a milder, slightly sweet flavor and similar texture. Use equal amounts.
- quinoa, cooked → Cooked brown rice, white rice, or farro. Brown rice adds an earthy flavor; white rice is milder. Farro is nutty and chewy. Use equal volumes.
- panko breadcrumbs → Regular breadcrumbs, crushed saltine crackers, or crushed potato chips. Regular breadcrumbs are finer and may pack more tightly; use slightly less. Crackers or chips add savory flavor.
