Brussels Sprouts Quinoa Casserole

Picture a casserole dish emerging from the oven, its panko crust bronzed and crackling, ribbons of Gruyère bubbling at the edges, and the sweet, nutty aroma of seared Brussels sprouts mingling with thyme and garlic.

Imagine spooning into a creamy, quinoa-studded center—tender sprouts, silky mushrooms, and a whisper of Dijon—comfort that’s colorful, hearty, and nourishing in every bite.

I love this dish because it proves weeknight food can feel like a hug without slowing you down; it’s wholesome but still special, the kind of dinner that brings everyone to the table.

It’s one-pan cozy for busy weeknights, a crowd-pleaser for Sunday suppers, and sturdy enough for meal prep when life’s a whirlwind.

When a hectic school concert night collided with late meetings, this casserole baked while we regrouped—hands free, stress low, plates clean.

Ready? Let’s cook!

Why You’ll Love It

• Delivers bold flavor with seared sprouts and creamy Gruyère sauce
• Packs protein and fiber from quinoa and Greek yogurt
• Assembles ahead easily for stress-free weeknight baking
• Offers flexible swaps for cheeses and broths
• Finishes with craveable crunchy, golden panko topping

Ingredients

• 1 cup quinoa, rinsed — removes bitterness (look for pearly, intact grains)
• 2 cups low-sodium vegetable broth — for fluffy, flavorful quinoa (choose clean-label)
• 1.5 pounds Brussels sprouts, trimmed and halved — even halves sear best (pick tight, small heads)
• 1 medium yellow onion, finely chopped — sweet base flavor (firm, no soft spots)
• 3 cloves garlic, minced — aromatic lift (use fresh, not jarred, for best bite)
• 1 cup cremini mushrooms, sliced — umami depth (choose dry, unblemished caps)
• 1 cup shredded Gruyère cheese — melts creamy with nutty taste (freshly shredded)
• 1/2 cup grated Parmesan cheese — savory finish (use real Parmigiano Reggiano)
• 1 cup milk, warmed — helps smooth the sauce (2% or whole)
• 1/2 cup plain Greek yogurt — tangy richness (full-fat for silkier texture)
• 2 tablespoons olive oil — for searing and topping (use a robust everyday EVOO)
• 2 tablespoons unsalted butter — for the roux (keeps salt control)
• 2 tablespoons all-purpose flour — thickens the sauce (scoop-and-level)
• 1 teaspoon Dijon mustard — subtle sharpness (smooth, not grainy)
• 1/2 teaspoon smoked paprika — gentle smokiness (fresh, vibrant color)
• 1/2 teaspoon dried thyme — herbal notes (rub to release oils)
• 1/4 teaspoon crushed red pepper flakes — mild heat (adjust to taste)
• 1 teaspoon kosher salt — seasons evenly (use Morton or Diamond Crystal)
• 1/2 teaspoon black pepper — balances richness (freshly ground)
• 1/2 cup panko breadcrumbs — crunchy topping (light, airy texture)
• 2 tablespoons chopped fresh parsley — fresh finish (add just before serving)

Step-by-Step Method

Preheat & Prep

Preheat oven to 375°F (190°C). Grease a 9×13-inch baking dish. Rinse quinoa under cold water to remove bitterness. Warm the milk gently so it doesn’t seize when added later. Trim and halve Brussels sprouts. Finely chop onion, slice mushrooms, and mince garlic. Gather cheeses, spices, and remaining ingredients to streamline cooking.

Simmer the Quinoa

Combine rinsed quinoa and vegetable broth in a large saucepan. Bring to a boil, then reduce heat to low. Cover and simmer until liquid is absorbed and grains are fluffy, about 15 minutes. Remove from heat and fluff with a fork. Keep covered to stay warm while you prepare the vegetables and sauce.

Sear the Brussels Sprouts

Heat olive oil in a large skillet over medium-high heat. Arrange Brussels sprouts cut-side down in a single layer. Sear without moving until deeply browned, 4 to 5 minutes. Flip and cook briefly to soften. Browning builds sweetness and balances bitterness. Transfer to one side of the skillet to make space for aromatics.

Soften Onions & Mushrooms

Add onion and mushrooms to the open side of the skillet. Cook, stirring occasionally, until softened and lightly browned, about 4 minutes. Stir in minced garlic and cook for 30 seconds until fragrant. Keep heat moderate to prevent burning. Toss everything together so flavors mingle while maintaining some texture.

Build the Roux

Push vegetables to the edges, creating a clear center. Melt butter in the middle, then sprinkle in flour. Whisk constantly for 1 minute to cook off raw flour taste. Keep the roux pale for a delicate, creamy sauce. Make certain no dry spots remain. Maintain steady heat to avoid scorching or lumps.

Whisk in Warm Milk

Gradually pour in warm milk while whisking. Stir until smooth, glossy, and lightly thickened, 2 to 3 minutes. Scrape the pan bottom to incorporate fond. Aim for a sauce that coats the spoon. Reduce heat if it bubbles too vigorously. Seasoning will be added next to round out the flavor.

Season the Sauce

Remove skillet from heat. Whisk in Greek yogurt, Dijon mustard, smoked paprika, dried thyme, crushed red pepper flakes, kosher salt, and black pepper. Taste and adjust seasoning as needed. The yogurt adds tang and creaminess. The mustard enhances savoriness. Keep the mixture silky and cohesive.

Fold in Quinoa & Cheese

Add cooked quinoa to the skillet and fold gently to combine with vegetables and sauce. Stir in half of the shredded Gruyère until just melted and evenly distributed. Keep the mixture cohesive but not mushy. Make certain even dispersal of Brussels sprouts and mushrooms for balanced bites throughout.

Assemble & Top

Transfer the mixture to the greased baking dish, smoothing into an even layer. Sprinkle the remaining Gruyère evenly over the top, followed by grated Parmesan. Toss panko with a drizzle of olive oil, then scatter over the cheeses. The layered topping makes certain a crisp, golden crust after baking.

Bake & Finish

Cover loosely with aluminum foil and bake for 20 minutes. Remove foil and continue baking until bubbly and golden, 10 to 12 minutes more. Let the casserole rest for 5 minutes to set. Garnish with chopped fresh parsley. Serve warm. Add a squeeze of lemon or toasted nuts if desired.

Ingredient Swaps

• Cheese: Swap Gruyère with sharp cheddar, fontina, Swiss, or mozzarella; use lactose-free cheese to reduce lactose.
• Dairy-free: Replace milk with unsweetened oat/almond milk; use vegan yogurt (plain, unsweetened) and vegan cheeses; butter → olive oil.
• Gluten-free: Use cornstarch (1 tbsp) instead of flour and gluten-free panko.
• Protein boost: Stir in cooked chickpeas, white beans, or diced rotisserie chicken (if not vegetarian).
• Mushrooms: Substitute with zucchini, cauliflower florets, or bell peppers.
• Broth: Use chicken broth instead of vegetable for non-vegetarian; water plus 1 tsp bouillon as budget option.
• Heat/flavor: Swap smoked paprika with regular paprika + a dash of liquid smoke; Dijon → whole-grain or 1/2 tsp mustard powder.
• Herbs: Dried thyme → Italian seasoning or herbes de Provence; add fresh thyme if available.
• Topping: Panko → crushed Ritz/saltines, cornflake crumbs, or toasted chopped nuts for crunch.

You Must Know

• Doneness • If the center looks set but edges bubble aggressively, tent briefly and check texture by inserting a spoon: casserole should feel creamy, not soupy, and a thermometer reads 165°F+ in the middle after 30–32 minutes total; cheese on top should be spotty-golden with crisp panko.
• Troubleshoot • When the sauce feels thin after adding milk/yogurt, hold over gentle heat and stir 2–3 more minutes until it lightly coats the back of a spoon; the bubbles should look slower and glossy—this prevents a watery casserole.
• Flavor Boost • For deeper savor, season the sprouts and mushrooms with an extra 1/4 teaspoon kosher salt right after they pick up color, then finish the assembled dish with a 1–2 teaspoon squeeze of lemon and a few grates of nutmeg; taste for a balanced salty-savory-bright finish.
• Swap • If Gruyère isn’t available, use 1 cup sharp white cheddar or 1 cup fontina; keep Parmesan as is. For dairy-light, replace 1 cup milk with 3/4 cup milk + 1/4 cup unsalted broth; meltability and browning remain similar.
• Scale • For 8–10 servings, increase all ingredients by 1.5x and use a deep 9×13 or two 8×8 pans; covered time becomes about 25 minutes, then 12–14 minutes uncovered—look for the same bubbly edges and 165°F center.

Serving Tips

• Serve with a simple arugula salad and lemon vinaigrette for brightness.
• Add a fried or poached egg on top for extra richness.
• Pair with crisp white wine or sparkling water with lemon.
• Plate in warm bowls; finish with extra parsley and a lemon squeeze.
• Offer toasted almonds or walnuts at the table for added crunch.

Storage & Make-Ahead

Refrigerate leftovers in an airtight container for 3–4 days.

Reheat covered at 350°F or in the microwave with a splash of milk to keep creamy.

Assemble up to 24 hours ahead and bake as directed, adding 10 minutes covered.

Freezes well up to 2 months.

Thaw overnight before reheating.

Reheating

Reheat gently.

Microwave covered portions with a splash of milk at 50% power, stirring once.

Oven at 325°F, covered, 15–20 minutes.

Stovetop on low heat with a little broth, stirring to prevent sticking.

Midwestern Potluck Favorite

Often the first empty dish on a church-basement table, this Brussels Sprouts Quinoa Casserole brings snug, Midwest comfort with a fresh twist. I bring it to potlucks when the weather leans gray and everyone craves warm, familiar flavors with a little sparkle.

The quinoa keeps it hearty yet light; Gruyère and Parmesan melt into creamy pockets that hug the seared sprouts. You’ll taste sweet onion, earthy mushrooms, and a quiet nudge of Dijon and smoked paprika.

I bake it in a 9×13 so it travels easily, then finish with buttery panko for a golden, audible crunch. It slices cleanly, serves six generous squares, and holds heat on a buffet.

Add a scatter of parsley and watch plates return scraped clean.

Final Thoughts

Ready to cozy up with this Brussels Sprouts Quinoa Casserole? Give it a try as written or make it your own—swap the cheese, add a squeeze of lemon, or toss in toasted nuts for extra crunch.

Frequently Asked Questions

Can I Freeze Individual Portions for Quick Lunches?

Yes—you can freeze individual portions for quick lunches. I cool, slice, wrap snugly, and freeze. Reheat from frozen, covered, until steamy; add a splash of broth to refresh. It emerges cozy, fragrant, and perfectly satisfying.

How Can I Make It Dairy-Free Without Sacrificing Creaminess?

Swap milk, yogurt, and cheese for silky cashew cream, creamy oat milk, and melty dairy-free mozzarella. I whisk in nutritional yeast, a dab of Dijon, and olive-oil-toasted panko. You’ll taste plush warmth, not miss dairy.

What Wine Pairs Best With This Casserole?

I’d pour a crisp Chardonnay or Grüner Veltliner; both hug the nutty quinoa and savory greens. If you prefer red, I’d choose a light Pinot Noir—silky berries, gentle earth, candlelit warmth, your casserole glowing, flavors humming.

How Do I Prevent a Soggy Panko Topping?

I toss panko with olive oil, salt, and a kiss of Parmesan, then bake uncovered until golden. I avoid excess moisture, cool the filling briefly, and finish under the broiler for a whisper-crisp, hearth-warm crunch.

Can I Cook Quinoa in a Rice Cooker for This Recipe?

Yes—you can. I cook rinsed quinoa in a rice cooker with a 1:2 quinoa-to-broth ratio. Let it steam on warm five minutes, fluff with a fork, and it emerges tender, nutty, and perfectly ready.