Asparagus Mushroom Frittata Sourdough

Last spring, I found myself with a half loaf of sourdough going stale and a CSA box overflowing with asparagus. Rather than toss either, I imagined layering that bread into a crispy foundation and building a vegetable-laden frittata on top. The result was so stunning—golden, fragrant, and sturdy enough to slice cleanly—that it became my go-to move whenever I needed to feed a crowd without fussing.

I made this for a friend who'd just moved into a tiny apartment with barely a stove worth mentioning. Watching her pull it from the oven, all puffy and golden, felt like proof that even in a cramped kitchen, you could create something that looked and tasted like effort.

Ingredients

• Sourdough bread, 6 slices with crusts removed: The bread creates a structural base that soaks up just enough egg custard to become tender without turning mushy; day-old is actually better than fresh here.
• Unsalted butter, 2 tbsp melted: This prevents sticking and adds a golden richness to the crust layer.
• Asparagus, 1 cup trimmed and cut into 1-inch pieces: Spring asparagus cooks quickly and stays tender-crisp; woody ends should be snapped off where they naturally break.
• Cremini or button mushrooms, 1 cup sliced: These earthy fungi add umami depth and a meaty texture that balances the delicate vegetables.
• Shallot, 1 small finely chopped: A shallot's gentle sweetness won't overpower the other flavors the way a larger onion might.
• Olive oil, 2 tbsp: Use your better oil here since it's the primary fat for sautéing vegetables.
• Large eggs, 8: Fresh eggs with bright, firm yolks make the biggest difference in final texture.
• Whole milk, 1/3 cup: This adds richness without overwhelming the eggs' delicate structure.
• Heavy cream, 1/4 cup: A small amount keeps the frittata creamy at its center even after cooling.
• Gruyère cheese, 1/2 cup grated: Gruyère melts beautifully and brings a subtle nuttiness that complements vegetables.
• Parmesan cheese, 1/4 cup grated: The sharpness adds contrast and helps the frittata set up slightly firmer.
• Fresh chives, 2 tbsp chopped: Chives taste brightest when scattered right before serving or folded in just before baking.
• Salt and black pepper to taste: Season boldly—the frittata should taste good before it even bakes.

Instructions

Prepare your pan and preheat the oven:

Set your oven to 375°F and lightly butter a 9-inch springform pan or deep pie dish; a cold oven means uneven cooking. Having everything ready before you start cooking keeps momentum going.

Line the pan with sourdough:

Arrange bread slices to cover the bottom and sides, overlapping slightly so no gaps remain. Brush generously with melted butter, then bake for 8 to 10 minutes until the bread firms up and just begins to smell toasted.

Sauté the vegetables:

Heat olive oil in a skillet over medium heat and cook the chopped shallot until it softens and becomes fragrant, then add mushrooms. Once the mushrooms release their moisture and begin to brown at the edges (about 4 minutes total), add the asparagus pieces and cook for another 2 to 3 minutes, just until they brighten and become tender-crisp.

Build the egg custard:

Whisk together eggs, milk, cream, both cheeses, chopped chives, salt, and pepper in a large bowl until completely combined and the mixture looks pale and slightly frothy. Taste it and adjust seasoning—you want it to taste almost slightly oversalted since eggs dilute salt perception.

Assemble and bake:

Spread the sautéed vegetables evenly across the sourdough crust, then pour the egg mixture over everything, letting it settle into the gaps. Bake for 25 to 30 minutes, watching for the edges to puff and turn golden while the very center still jiggles slightly when you gently shake the pan.

Cool and serve:

Let the frittata rest for 5 minutes before slicing—this brief rest helps it hold together. Serve warm or at room temperature with a simple salad on the side.

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I served this to my elderly neighbor who'd been living alone since his wife passed, and he sat at my kitchen counter eating a slice while telling me stories I'd never heard before. Food can open doors that polite conversation sometimes can't.

Why the Sourdough Crust Works

Sourdough's inherent tang and chewy structure absorb custard without disintegrating the way softer breads would. The crust transforms into something crispy-edged and tender-centered, almost like a cross between focaccia and bread pudding. When you slice into it, you get structural integrity and texture variation in every bite.

Adapting This for Your Kitchen

If you don't have a springform pan, a regular 9-inch pie dish works just fine—you'll just need a knife to loosen the edges before serving instead of unclipping the sides. The frittata is forgiving; you can swap in different vegetables depending on what's in season or what you have hanging around.

From Pantry to Table

This is one of those dishes that rewards preparation and planning slightly, but doesn't demand it. You can sauté the vegetables an hour before baking if that fits your morning better, and the whole project still feels manageable.

• Serve this with crusty bread and a crisp white wine like Sauvignon Blanc for a complete meal that feels special without exhausting you.
• Leftover frittata keeps beautifully for three days in the refrigerator and tastes wonderful cold straight from the fridge or gently warmed.
• For a non-vegetarian version, crumble cooked pancetta or scatter smoked salmon over the vegetables before pouring the egg mixture.

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This frittata has become my answer to the question of what to cook when I want something that looks like I tried but tastes effortless. It's built on the understanding that the simplest dishes are often the most satisfying.

Recipe Questions & Answers

→ How is the sourdough crust prepared?

Sourdough bread slices are trimmed and arranged to line a springform pan, brushed with melted butter, and baked until crisp to form a sturdy crust.

→ What vegetables are included in the dish?

Fresh asparagus cut into pieces and sliced cremini or button mushrooms sautéed with shallots provide the vegetable components.

→ Which cheeses enhance the flavor?

Gruyère and Parmesan cheeses are grated and mixed into the egg base to add a rich, savory taste.

→ Can this dish accommodate dietary preferences?

For dairy-free diets, plant-based milk and cheese alternatives can be used. Additional proteins like pancetta or smoked salmon can be added for non-vegetarian options.

→ What is the ideal cooking temperature and time?

Bake the layered mixture at 375°F (190°C) for 25–30 minutes until the top is puffed and golden with a just-set center.