Here’s a savory, custardy Cheesy Spinach and Mushroom Strata—a layered, make-ahead bread casserole that’s perfect for brunch, lunch, or a meatless dinner.
Ingredients
Serves 8–10
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1 Tbsp olive oil
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1 Tbsp unsalted butter
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1 medium onion, diced
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3 cloves garlic, minced
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8 oz cremini or white mushrooms, sliced
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5 oz fresh spinach (about 5 packed cups), roughly chopped
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8 cups day-old bread, cut into 1-inch cubes (rustic Italian, sourdough, or French)
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8 large eggs
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2 ½ cups whole milk
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1 Tbsp Dijon mustard
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½ tsp salt, plus more to taste
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½ tsp black pepper
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¼ tsp freshly grated nutmeg (optional, excellent with spinach)
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6 oz Gruyère or Swiss cheese, shredded (about 1½ cups)
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4 oz sharp white cheddar, shredded (about 1 cup)
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2 Tbsp grated Parmesan cheese
Instructions
1. Sauté the vegetables
Heat the olive oil and butter in a large skillet over medium heat. Add the onion and cook until softened, about 4 minutes. Add the garlic and mushrooms, season with a pinch of salt, and cook until the mushrooms release their liquid and begin to brown, 6–8 minutes. Add the spinach in handfuls, stirring until completely wilted. Remove from heat and let cool slightly.
2. Prepare the custard
In a large bowl, whisk together the eggs, milk, Dijon mustard, salt, pepper, and nutmeg until fully combined.
3. Assemble the strata
Grease a 9×13-inch (3-quart) baking dish. Spread half of the bread cubes evenly in the dish. Top with half of the mushroom-spinach mixture, then half of both cheeses. Repeat the layers with the remaining bread, vegetables, and cheeses. Slowly pour the custard evenly over the entire dish, making sure all the bread gets soaked. Gently press down on the top layer with a spatula to submerge the bread.
4. Rest (essential step)
Cover with plastic wrap and refrigerate for at least 2 hours, or ideally overnight. This allows the bread to fully absorb the custard, giving you a creamy interior and a puffed, golden top.
5. Bake
Preheat oven to 350°F (175°C). Remove the plastic wrap, sprinkle the Parmesan over the top, and bake uncovered for 50–60 minutes, until the top is deeply golden and the center is set with just a slight jiggle. A knife inserted in the center should come out clean. Let it rest for 10–15 minutes before slicing.
Make It Your Own
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Add protein: Crispy bacon, cooked crumbled sausage, or diced ham all work.
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Cheese swaps: Fontina melts beautifully; feta or goat cheese add tang.
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Bread choice: Slightly stale, hearty bread holds up best. Avoid soft, pre-sliced sandwich bread—it turns to mush.
Let me know if you’d like a smaller (8×8) version or want to add a different vegetable. 😊