Creamy Mushroom and Spinach Pasta with Caramelized Onions

Creamy mushroom spinach pasta with caramelized onions, smothered in Parmesan cheese cream sauce.  Tastes just like a first course from an Italian restaurant.  Caramelized onions add so much needed flavor to this meatless pasta. I use long pasta, such as fettuccine noodles, which work perfectly with the long strands of caramelized onions.

What makes this mushroom spinach pasta special?

• The recipe uses basic, easy-to-find ingredients. In fact, the recipe uses just a few ingredients.  Everything you use in this recipe can be found in most grocery stores.
• Pasta with mushrooms and spinach can be quite bland. Not this one, though! Why? First, caramelized onions add incredible flavor dimension. Second, you smother everything in a cream sauce. This pasta is anything BUT bland.
• I use shiitake mushrooms that provide rich, meaty flavor to the pasta.
• You don’t need meat for this meatless pasta dish. To reinforce my point #2, pasta with mushrooms and spinach could be bland and therefore require meat. But because of the cream sauce and the caramelized onions, you will feel that this is a complete meal that doesn’t even need meat.

Using shiitake mushrooms in a pasta dish

In this recipe I use shiitake mushrooms. Why? Because they have a rich, meaty flavor which complements creamy pasta perfectly. Remember my point early on that this recipe doesn’t need meat? Well, just try shiitake mushrooms and you’ll see why.  Shiitake mushrooms provide thick, chewy, yet soft texture and add “meaty” component to this spinach pasta.

Although I love shiitake mushrooms in this pasta, you, of course, can substitute all kinds of other mushrooms for shiitake. If you can’f find shiitake, use portobello mushrooms or cremini mushrooms – both of these will be excellent substitutions for shiitake.

Substitutions

• I use fettuccine noodles (wide long pasta). You can also use spaghetti, linguine, angel hair pasta. I do prefer to use long pasta in this recipe vs. short pasta, such as penne. Long pasta makes a better presentation with caramelized onions, spinach, and mushrooms.
• To make this pasta gluten free, use gluten free fettuccine or any other type of long gluten free pasta.  Gluten free brown rice fettuccine will work great!
• To make cream sauce I use heavy cream + milk. You can totally substitute half and half for that (in the same amounts).
• Don’t have shiitake mushrooms? Use portobello or cremini mushrooms.  

To top it all, this spinach and mushroom pasta turned out to be quite versatile, too. You could definitely eat this creamy pasta loaded with vegetables as a stand-alone, meatless dish. It also makes a surprisingly great side dish for a grilled steak, pork or chicken. In fact, this pasta recipe happens to combine all of my 4 favorite sides for steak in one: mushrooms, creamed spinach, caramelized onions, and creamy pasta with cheese.

So, feel free to eat this pasta as a stand-alone meatless dinner or add a piece of grilled steak, pork, or chicken.

How to make Creamy Mushroom Spinach Pasta with Caramelized Onions

Here are some step-by-step photos illustrating how to make this pasta. Scroll all the way down for complete recipe.

First, caramelize onions for 30 minutes to reach a nice deep brown color.  (See:  how to caramelize onions) Deglaze with a small amount of balsamic vinegar.

Next, cook shiitake mushrooms (without stems) in 1 tablespoon of olive oil. You can use any type of mushrooms of small size.

Then, add spinach to caramelized onions and mushrooms mixture, stir until spinach wilts.

Next, add heavy cream, milk, Parmesan cheese and salt to the vegetables mixture.

Add cooked and drained pasta and cook for 5-10 minutes on low heat so that creamy sauce coats pasta and Parmesan cheese melts and coats pasta as well.

Tips for making pasta sauce super creamy

Does your cream sauce clump as you’re trying to make it? Or, does the sauce separate in the process? Here is how to avoid and fix all these problems:

• Make sure your pan or skillet is very hot before you add the cream sauce ingredients. In this recipe, this is achieved by caramelizing the onions first, cooking the mushrooms, then wilting the spinach – all in the same skillet.  This ensures that the pan is already very well heated.
• Bring heavy cream and milk to a boil just for a second.  Immediately, add shredded Parmesan cheese, make sure everything is boiling. Then, immediately reduce everything to simmer. The point in doing all this is again to make sure your cooking pan/skillet is hot enough to handle the sauce. The cheese simply will not melt properly if the ingredients are not hot enough. Bringing everything to a short boil and then reducing heat to simmer (low boiling, but still boiling point) ensures melting of the cheese instead of clumping.
• Keep stirring the sauce at all times. This ensures again that the sauce is smooth and of consistent, even texture. Do not continue to boil the cream sauce. Bring everything to simmer immediately after reaching the boiling point as described above.
• If your sauce is too thick after adding the cheese, thin the sauce out by slowly adding milk (or half and half) while simmering the sauce. Make sure the sauce continues to simmer and does not come to a standstill, while you add milk to thin it out.

More delicious mushroom pasta recipes

I love combining mushrooms and pasta:

• If you want simplicity and you love garlic and butter, you’ll love this super easy meatless garlic and mushroom pasta, smothered in butter and shredded Parmesan.
• If you want meat, such as chicken, and enjoy more complex flavor, check out this chicken pesto pasta with mushrooms – it’s so creamy and the basil pesto sauce combines beautifully with chicken, pasta, and mushrooms.
• How about homemade vodka sauce with mushrooms?  And chicken?  Then definitely try one of my all time favorites: penne pasta in creamy vodka tomato sauce with mushrooms.

4.8 from 10 votes

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Creamy Mushroom Spinach Pasta with Caramelized Onions

Prep Time

20 mins

Cook Time

30 mins

Total Time

50 mins

 

This creamy pasta is loaded with spinach, mushrooms, caramelized onions, and then smothered in a creamy Parmesan cheese sauce.  This is a meatless pasta recipe that doesn't need any meat.  At the same time, it serves as an excellent side dish with grilled meats, such as steak, pork or chicken.  This mushroom spinach pasta is super versatile!  

Course: Main Course

Cuisine: Italian

Servings: 4 people

Calories: 588 kcal

Author: Julia

Ingredients

• 1 tablespoon olive oil
• 3 onions medium or large, sliced
• 1/4 teaspoon salt
• 1 tablespoon balsamic vinegar
• 1 tablespoon olive oil
• 10 oz mushrooms , sliced (I used shiitake)
• 6 oz spinach
• 8 oz fettuccine
• 2/3 cup heavy cream
• 1/3 cup milk
• 1 cup Parmesan cheese shredded
• 1/4 teaspoon salt

Instructions

How to caramelize onions:

1. Heat 1 tablespoon olive oil on high heat in a large skillet, when oil is heated, add sliced onions and cook on high heat for about 10 minutes, constantly stirring with spatula. The onions should start to brown, but without burning (a couple of onions may be burnt here and there, but overall they should not be charred). 

2. Reduce heat to medium and continue cooking onions for 10 more minutes, continuing to stir, as onions brown even more without burning. At this point add just a pinch of salt over onions. 

3. Continue cooking for 10 more minutes on medium or low heat, stirring occasionally to make sure onions don’t stick to the bottom of the pan or burn. Total you should have cooked onions for 30 minutes. 

4. Remove from heat and sprinkle onions with a small amount of balsamic vinegar to deglaze the pan. Using spatula, mix the onions, scraping the bottom of the pan and coating onions with a pinch of balsamic vinegar you just added.  Remove caramelized onions to a plate

How to cook mushrooms and spinach:

1. Heat 1 tablespoon olive oil in the same skillet, and add sliced mushrooms (I used shiitake with stems removed, you can use any small sized mushrooms). Add just a pinch of salt. 

2. Reduce heat to medium-low and cook mushrooms covered for about 20 minutes, occasionally stirring. 

3. NOTE: if you use other mushrooms (not shiitake) the cooking time will be much shorter, only about 5 minutes. Shiitake mushrooms need longer times to cook. If you use regular button mushroom – cook them for only about 5 minutes until they soften.

4. Add caramelized onions back to the skillet with cooked mushrooms.   Add 3 cups of fresh spinach and stir on low heat just until spinach wilts.

Cook pasta:

1. Cook pasta according to package instructions. Drain.

Make cream sauce:

1. Add heavy cream and milk to he mushroom-onions-spinach mixture and bring to a quick boil.

2. Immediately add shredded Parmesan cheese and 1/4 teaspoon salt and reduce heat to simmer (low boiling point).  Keep stirring to melt the cheese.  

3. Add cooked and drained pasta to the creamy sauce, stir to coat on low heat for about 5-10 minutes until Parmesan cheese melts completely and starts to coat pasta as well.

4. Serve on warm plates (warmed in the oven) as is, or with more parmesan cheese sprinkled on top.

Nutrition Facts

Creamy Mushroom Spinach Pasta with Caramelized Onions

Amount Per Serving

Calories 588 Calories from Fat 279

% Daily Value*

Total Fat 31g 48%

Saturated Fat 15g 75%

Cholesterol 121mg 40%

Sodium 768mg 32%

Potassium 801mg 23%

Total Carbohydrates 55g 18%

Dietary Fiber 4g 16%

Sugars 8g

Protein 22g 44%

Vitamin A 96.7%

Vitamin C 24%

Calcium 42.6%

Iron 16.5%

* Percent Daily Values are based on a 2000 calorie diet.

This recipe was originally published on January 22, 2013, and republished with updates, cooking tips in June 2018.