Egg and Cheese Croissant Casserole with Gruyère and Sumac

By , Test Kitchen Director · Reviewed by AislePrompt Editorial · ·

An elevated brunch casserole with flaky croissants soaked in a spiced egg custard, layered with nutty Gruyère cheese and a hint of tangy sumac. This french-inspired brunch ready in about 60 minutes combines shredded Gruyère cheese, large eggs, whole milk into a breakfast that fuels the morning without the midday crash — make-ahead-friendly and balanced enough to anchor the first meal of the day. Each serving lands at about 460 calories and feeds 6, so it sits comfortably in a weekly breakfast rotation alongside fruit, yogurt, or coffee. Tap "Plan a meal with the AI" below to drop this recipe into your week and send the ingredients straight to Instacart. Nutrition values are approximate, calculated from USDA FoodData Central (fdc.nal.usda.gov) — verify against ingredient labels for any health-driven dietary plan.

Prep: 15 min Cook: 45 min Serves 6 French cuisine 460 cal/serving
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Ingredients

Instructions

  1. Step 1: Preheat oven to 350°F. Butter a 9x13-inch baking dish generously to prevent sticking.
  2. Step 2: Spread 5 torn croissant pieces evenly in the baking dish and sprinkle 1 1/4 cups shredded Gruyère cheese evenly over the top.
  3. Step 3: In a large mixing bowl, whisk together 7 large eggs, 2 cups whole milk, 1/2 cup heavy cream, 1 1/2 tsp sumac, 1 tsp salt, and 1/2 tsp black pepper until completely blended.
  4. Step 4: Pour the egg mixture evenly over the croissant and cheese layers, gently pressing down with a spatula to submerge the croissants.
  5. Step 5: Let the casserole sit for 10 minutes to allow the croissants to soak up the custard.
  6. Step 6: Bake uncovered for 40-45 minutes until the top is puffed and golden and a knife inserted in the center comes out clean.
  7. Step 7: Remove from oven and allow to cool for 5 minutes before slicing and serving warm.

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Frequently asked questions

How long does Egg and Cheese Croissant Casserole with Gruyère and Sumac take to make?

Total time is about 60 minutes (15 min prep + 45 min cook). Most home cooks find this fits comfortably into a busy morning; prep components the night before to save active time.

How do I store leftover Egg and Cheese Croissant Casserole with Gruyère and Sumac?

Cool to room temperature within 2 hours, then store in an airtight container in the fridge for up to 4 days. Reheat in the microwave or oven; egg- or grain-based items may need a splash of milk or water to refresh texture. Cold-served items (overnight oats, smoothies) keep 2–3 days in the fridge.

Can I substitute ingredients in Egg and Cheese Croissant Casserole with Gruyère and Sumac?

Yes — most ingredients in this recipe have flexible swaps. For oil, use any neutral high-smoke-point oil (avocado, grapeseed, refined coconut). For aromatics, dried herbs at ⅓ the volume of fresh work in a pinch. The full ingredient list is shoppable on Instacart so you can see substitutes in real time.

How do I scale Egg and Cheese Croissant Casserole with Gruyère and Sumac for a different number of people?

The recipe is written for 6 servings. Multiply each ingredient by (your serving target / 6). Cook time stays roughly the same up to 2x; for 3-4x batches, switch from a skillet to a sheet pan or stockpot so the food isn't crowded — overcrowding steams instead of browns.

What goes well with Egg and Cheese Croissant Casserole with Gruyère and Sumac?

French brunch like this pair well with a simple grain (rice, couscous, or crusty bread), a quick salad with acid (lemon vinaigrette, pickled onions), and a pan sauce or yogurt-based dip. Tap "Plan a meal with the AI" to get specific side suggestions.

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