There’s something undeniably magical about a dish that layers flavors, textures, and pure comfort. This Mushroom and Caramelized Onion Lasagna isn’t your typical lasagna—it’s a tasty surprise where earthy mushrooms, sweet caramelized onions, and creamy béchamel come together in perfect harmony.
Whether you're hosting a dinner party or simply indulging in a cozy night at home, this recipe is guaranteed to steal the spotlight.
The Ultimate Mushroom and Caramelized Onion Lasagna: Step-by-Step Recipe
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Mushroom and Caramelized Onion Lasagna |
This Mushroom and Caramelized Onion Lasagna is a family favorite. I make it once a year for our Christmas dinner because it is just that special. Family members ask specifically whether this lasagna will be on the holiday dinner menu. They would be very disappointed to hear it is not.
I first discovered this delicious lasagna about twenty years ago, thanks to a talented caterer. I was hosting a holiday party for my work colleagues and asked her to create a menu that would shine on a buffet table. One of her suggestions was a mushroom lasagna, and it turned out to be the star of the evening—a hit with every single guest!
Secondly, I always use two - two and a half pounds of mushrooms per lasagna. More mushrooms make this a more substantial lasagna.
2. Don't Crowd the Mushrooms: Two and a half pounds of sliced mushrooms are a lot of mushrooms. You'll need a large frying pan to be sure there is enough space for the mushrooms to get a little brown on them. I use the large rectangular electric frying pan that gets the job done for me. If you have a smaller frying pan, split the amount of mushrooms in half when cooking them.
3: Grind Your Nutmeg: You should plan to grate fresh nutmeg for this lasagna. There aren't many ingredients in this dish so you'll want the nutmeg flavor to shine through. I have this nutmeg grater
that does the job for me.
4: Don't Rush Your Prep: Even though there are just a few ingredients in this lasagna, the process is time-consuming. I average about an hour and a half of preparation time when making this dish. You'll need to clean and slice the mushrooms, chop the onions, cook the onions and mushrooms, prepare the white sauce, and assemble the lasagna. This deliciousness takes time and is very much worth your effort.
5: Make Ahead: You can make this lasagna ahead of time and freeze prior to baking. Just be sure to thaw the lasagna completely before cooking for the best results. Thawing the lasagna overnight in your refrigerator works well. I like to use disposable aluminum baking dishes when making multiples of this lasagna for my freezer.
Heat two tablespoons of butter with the olive oil in a large skillet. Add the mushrooms to the pan. Leave them without turning until they are lightly browned on one side. Season with a ittle salt and pepper. Stir and continue cooking until soft. Remove to a bowl.
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Updated 12/28/2024
Of course, I asked the caterer for the recipe. Not surprisingly, it was an Ina Garten recipe. That recipe is the inspiration for my Mushroom and Caramelized Onion Lasagna.
How to Make Mushroom Lasagna
You'll love that the recipe is fairly simple in that the main focus is mushrooms. A simple white sauce binds the dish together.I've made a few changes to the original Barefoot Contessa recipe over the years.
First, I always use Crimini mushrooms because they are easier to find at my local stores than the larger Portobello mushrooms, but you can use whatever kind of whole mushrooms look best in your market.
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Crimini Mushrooms are Perfect for Mushroom Lasagna |
Lastly, Adding caramelized onions adds a little extra flavor.
Tips for Mushroom Lasagna Success
1. Whole Mushrooms for Uniformity: I purchase whole mushrooms for this dish to control the size of the mushroom slices. You can use pre-sliced mushrooms to speed the preparation. Cleaning and slicing two and a half-pound of mushrooms can be a tedious and time-consuming process so purchasing already sliced mushrooms will shorten your prep time.
2. Don't Crowd the Mushrooms: Two and a half pounds of sliced mushrooms are a lot of mushrooms. You'll need a large frying pan to be sure there is enough space for the mushrooms to get a little brown on them. I use the large rectangular electric frying pan that gets the job done for me. If you have a smaller frying pan, split the amount of mushrooms in half when cooking them.
3: Grind Your Nutmeg: You should plan to grate fresh nutmeg for this lasagna. There aren't many ingredients in this dish so you'll want the nutmeg flavor to shine through. I have this nutmeg grater
4: Don't Rush Your Prep: Even though there are just a few ingredients in this lasagna, the process is time-consuming. I average about an hour and a half of preparation time when making this dish. You'll need to clean and slice the mushrooms, chop the onions, cook the onions and mushrooms, prepare the white sauce, and assemble the lasagna. This deliciousness takes time and is very much worth your effort.
5: Make Ahead: You can make this lasagna ahead of time and freeze prior to baking. Just be sure to thaw the lasagna completely before cooking for the best results. Thawing the lasagna overnight in your refrigerator works well. I like to use disposable aluminum baking dishes when making multiples of this lasagna for my freezer.
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Mushroom Lasagna from Simple Ingredients |
The Steps
Clean your mushrooms by brushing them gently with a towel or a pastry brush. Trim the stems and slice the mushrooms.Heat two tablespoons of butter with the olive oil in a large skillet. Add the mushrooms to the pan. Leave them without turning until they are lightly browned on one side. Season with a ittle salt and pepper. Stir and continue cooking until soft. Remove to a bowl.
Add the onion to the pan. Season the onion with a little salt and pepper. Cook the onion until lightly browned and caramelized. Remove to the bowl with the mushrooms.
Heat the milk in a heat-safe, four-cup measuring cup in your microwave or in a pot on your stove. Melt a stick of butter in a saucepan over medium heat. Add the flour to the melted butter and cook for about a minute. Add the hot milk to the butter mixture, stirring to combine. Season with salt, pepper, and the nutmeg. Stir and keep cooking until the sauce thickens. You'll be able to draw a line through the sauce on the back of your spoon when it is ready. Remove the sauce from the heat.
Cook the lasagna noodles according to the package directions.
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Crimini Mushroom and Caramelized Onion Lasagna Filling |
Heat the milk in a heat-safe, four-cup measuring cup in your microwave or in a pot on your stove. Melt a stick of butter in a saucepan over medium heat. Add the flour to the melted butter and cook for about a minute. Add the hot milk to the butter mixture, stirring to combine. Season with salt, pepper, and the nutmeg. Stir and keep cooking until the sauce thickens. You'll be able to draw a line through the sauce on the back of your spoon when it is ready. Remove the sauce from the heat.
Cook the lasagna noodles according to the package directions.
To assemble, spread a few spoonfuls of sauce in the bottom of your lasagna pan
. Spread four lasagna noodles over the sauce. Add a layer of sauce to the noodles. Spread one-third of the mushroom and onion mixture over the sauce. Sprinkle with 1/4 cup of Parmesan cheese.
Complete two more layers of noodles, sauce, mushroom mixture, and Parmesan cheese. Top with a final layer of noodles, sauce, and Parmesan cheese.
Bake the lasagna in a preheated 375 degrees F oven for approximately 45 minutes or until browned on top and bubbly. Let sit for twenty to thirty minutes before serving. You absolutely want to let the layers set before cutting the lasagna. This mushroom lasagna also tastes great at room temperature.
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A Mushroom and Caramelized Onion Lasagna Ready to Bake |
Bake the lasagna in a preheated 375 degrees F oven for approximately 45 minutes or until browned on top and bubbly. Let sit for twenty to thirty minutes before serving. You absolutely want to let the layers set before cutting the lasagna. This mushroom lasagna also tastes great at room temperature.
Mushroom and Onion Lasagna Recipe
Yield: 10

Mushroom and Onion Lasagna
A tasty vegetable lasagna where earthy mushrooms, sweet caramelized onions, and creamy béchamel come together in perfect harmony.
Prep time: 60 MinCook time: 45 MinTotal time: 1 H & 45 M
Ingredients
Instructions
- Clean your mushrooms by brushing them gently with a towel or a pastry brush. Trim the stems and slice the mushrooms.
- Heat two tablespoons of butter with the olive oil in a large skillet. Add the mushrooms to the pan. Leave them without turning until they are lightly browned on one side. Season with a little salt and pepper. Stir and continue cooking until soft. Remove to a bowl.
- Add the onion to the pan. Season the onion with a little salt and pepper. Cook the onion until lightly browned and caramelized. Remove to the bowl with the mushrooms.
- Heat the milk in a heat-safe, four-cup measuring cup in your microwave or a pot on your stove.
- Melt eight tablespoons of butter in a saucepan over medium heat. Add the flour to the melted butter and cook for about a minute. Add the hot milk to the butter mixture, stirring to combine. Season with salt, one teaspoon of pepper, and the nutmeg. Stir and keep cooking until the sauce thickens. You'll be able to draw a line through the sauce on the back of your spoon when it is ready. Remove the sauce from the heat.
- Cook sixteen lasagna noodles according to the package directions. Spread a few spoonfuls of sauce in the bottom of your lasagna pan.
- Spread lasagna noodles over the sauce, overlapping slightly. Add a layer of sauce to the noodles. Spread one-third of the mushroom and onion mixture over the sauce. Sprinkle with 1/4 cup of Parmesan cheese. Complete two more layers of noodles, sauce, mushroom mixture, and Parmesan cheese. Top with a final layer of noodles, sauce, and Parmesan cheese.
- Preheat your oven to 375 F. Bake the lasagna for 45 minutes or until heated though, bubbly, and lightly browned on top.
- Let the lasagna rest for 15 to 30 minutes before serving.
Notes
The number of lasagna noodles you need will vary with the size of your pan.
Nutrition Facts
Calories
447Fat (grams)
21 gSat. Fat (grams)
11 gCarbs (grams)
49 gFiber (grams)
3 gNet carbs
46 gSugar (grams)
9 gProtein (grams)
16 gSodium (milligrams)
940 mgCholesterol (grams)
51 mgNutritional information is approximate.
©Just One Donna
Updated 12/28/2024
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