Portobello Mushroom Lasagna Is Where It’s At

I made lasagna for dinner last night.

Portobello spinach lasagna.

It was incredible.

You should probably make some, too.

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A friend passed along this gem of a recipe (thanks, Bethany!), and I’m super glad she did. For one, it meant that I got to use the lovely lasagna pan Kevin and I got for our wedding for about the second time. (The first time I used it to make this butternut squash lasagna, which I also highly recommend.) Secondly, I just found a new favorite recipe, which is awesome. AND it meant I got to visit Trader Joe’s over  the weekend, which is always a plus. (Actually, I went to TJ’s both Saturday and Sunday. I think they’re going to start knowing my name. For serious. And I’m totally fine with that.)

I was into making the prep for this meal as easy as possible, so I went for the pre-sliced baby portobello mushrooms (I used two packs) from Trader Joe’s as well as an already-grated Parmesan/Asiago cheese blend. I accidentally grabbed no-boil lasagna noodles rather than the regular kind (which is what the recipe calls for), but I ended up really liking the fact that I got to eliminate that step, so I’ve modified the recipe below to reflect that. I also added spinach (bagged and pre-washed), which makes just about everything better (even smoothies, and especially things with mushrooms).

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I prepped the lasagna Sunday afternoon, so all I had to do last night was pop it in the oven. 45 minutes later, we had a delicious dinner that was perfect for a chilly winter night!


  • Kosher salt
  • Olive oil
  • 3/4 pound no-boil lasagna noodles
  • 4 cups whole milk
  • 12 tablespoons (11/2 sticks) unsalted butter, divided
  • 1/2 cup all-purpose flour
  • 1 teaspoon freshly ground black pepper
  • 1 teaspoon ground nutmeg
  • 1 1/2 pounds portobello mushrooms
  • 2 cups fresh spinach leaves
  • 1 cup freshly ground Parmesan


  • Preheat the oven to 375 degrees (if you’re baking the lasagna immediately, of course, rather than prepping in advance like I did)
  • For the white sauce, bring the milk to a simmer in a saucepan. Set aside. Melt 8 tablespoons (1 stick) of the butter in a large saucepan. Add the flour and cook for 1 minute over low heat, stirring constantly with a wooden spoon. Pour the hot milk into the butter-flour mixture all at once. Add 1 tablespoon salt, the pepper, and nutmeg, and cook over medium-low heat, stirring first with the wooden spoon and then with a whisk, for 3 to 5 minutes, until thick. Set aside off the heat. (Note: I added a bit of corn starch to thicken my sauce a little more.)
  • Heat 2 tablespoons of oil and 2 tablespoons of the butter in a large saute pan. When the butter melts, add half the mushrooms and half the spinach, sprinkle with salt, and cook over medium heat for about 5 minutes, until the mushrooms are tender and they release some of their juices. If they become too dry, add a little more oil. Toss occasionally to make sure the mushrooms cook evenly. Repeat with the remaining mushrooms and spinach and set all vegetables aside.
  • To assemble the lasagna, spread some of the sauce in the bottom of a lasagna pan. Arrange a layer of noodles on top, then more sauce, then 1/3 of the mushrooms, and 1/4 cup grated cheese. Repeat 2 more times, layering noodles, sauce, mushrooms, and cheese. Top with a final layer of noodles and sauce, and sprinkle with the remaining cheese. (Note: Next time I make this for just Kevin and me, I think I’ll try splitting this recipe between three smaller baking dishes and freeze them. One whole lasagna is a lot for just two people!)
  • Bake uncovered for 45 minutes, or until the top is browned the sauce is bubbly and hot. Allow to sit at room temperature for 15 minutes and serve hot.

Add some red wine and a side salad (and perhaps some good toasted bread) and dinner is served!

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