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These Easy Stuffed Mushrooms are made with portabella mushrooms filled with mashed potatoes, wild rice, two kinds of cheese, garlic, and Mediterranean herbs. Packed with mouthwatering savory flavors, these perfectly bite-size stuffed mushrooms are the perfect vegetarian and gluten-free appetizer.

Cheesy Stuffed Mushrooms with Caramelized Onions

Mushrooms never fail to amaze me. I mean, they’re not the first thing I think to cook or serve to guests, but whenever I do, the results are always fabulous.

These stuffed mushrooms are super easy to make. Stuffed with either homemade mashed potatoes or instant mashed potatoes, wild rice (the chewy texture is really nice, promise), and topped with fresh herbs, caramelized onions, and a little sprinkle of cheese – each bite is the perfect combo of flavors.

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Of course, portabella mushrooms are a perfect, versatile blank canvas. Adapt and modify these stuffed mushrooms with whatever you’d like! If you don’t have time to caramelize the onions, simply top the mushrooms with more cheese and bacon bits.

Cheesy Stuffed Mushrooms with Caramelized Onions up close

How to Make Easy Stuffed Mushrooms

  1. Preheat the oven to 350° F and line a baking sheet with parchment paper. Prepare the mushroom caps and place them on a baking sheet.
  2. Caramelize the onions in a large skillet over medium-low heat for 40-45 minutes, stirring occasionally. Learn how to caramelize onions.
  3. Mix together your favorite instant mashed potatoes or prepare your favorite mashed potato recipe with the cooked wild rice, thyme, rosemary, garlic powder, salt, pepper, white cheddar cheese, and parmesan cheese in a medium bowl.
  4. Spoon the mashed potato mixture into the cavity of each mushroom. Top each mushroom with caramelized onions.
  5. Bake for 20 minutes, then sprinkle with parmesan and herbs and continue baking for 15-20 more minutes. Serve immediately.
Cheesy easy Stuffed Mushrooms with Caramelized Onions on a white plate in a row

Leftovers and Storage

Keep leftovers stored in an airtight container in the refrigerator for up to 2-3 days. Gently reheat in the microwave until warm.

More Appetizer Recipes

If you try making this Easy Stuffed Mushrooms Recipe, please leave me a comment and let me know! I always love to hear your thoughts.

Cheesy Mashed Potato and Herb Stuffed Mushrooms with Caramelized Onions as seen close up
Herb Stuffed Mushrooms
4.92 from 12 votes

Easy Stuffed Mushrooms Recipe


Close up photo of Chef Jessica Randhawa of The Forked Spoon in a blue spotted dress, in the sunlightJessica Randhawa
Packed with savory flavors, Easy Stuffed Mushrooms – with instant mashed potatoes, wild rice, two kinds of cheese, garlic, and Mediterranean herbs – are perfect for game day or a holiday appetizer.
Prep: 45 minutes
Cook: 45 minutes
Total: 1 hour 30 minutes
Servings: 18 servings
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Ingredients 

  • 18 baby portabella mushrooms, stems removed – 18 to 24 mushrooms
  • 1 tablespoon olive oil
  • 1 tablespoon butter
  • 1 large yellow onion, sliced
  • 2 packages Idaho Spuds Country Butter Mashed Potatoes, prepared
  • ½ cup cooked wild or white rice, optional
  • 1 teaspoon finely chopped fresh thyme
  • 1 teaspoon finely chopped fresh rosemary
  • ½ teaspoon garlic powder
  • 1 teaspoon salt
  • ½ teaspoon pepper
  • 1 cup white cheddar cheese, shredded
  • ½ cup grated parmesan cheese, plus more for topping

Instructions 

  • Preheat oven to 350 degrees F. Line a large baking sheet with parchment paper. Prepare mushroom caps and place them on prepared baking sheet. Set aside.
  • Heat a large skillet over medium low heat. Add olive oil and butter and cook onions for 40-45 minutes, stirring occasionally, or until onions are completely caramelized.
  • While the onions are cooking, prepare the mashed potato filling. In a medium bowl mix together the prepared Idaho Spuds Country Butter Mashed Potatoes with the cooked wild rice, fresh thyme, rosemary, garlic powder, salt, pepper white cheddar cheese and parmesan cheese. Taste mixture, adding more salt and pepper as needed.
  • With a small spoon add the cheesy mashed potato mixture into the cavity of each mushroom, squeezing in as much as you can. Each mushroom will hold a different amount, some more some less.
  • When the onions are finished caramelizing (so worth the wait!), carefully scoop a little on to the top of each mushroom cap. Place stuffed mushrooms in the oven and bake for 20 minutes. Remove from the oven and top each mushroom cap with a little extra parmesan and fresh herbs and continue to cook for an additional 15-20 minutes.
  • Best served immediately.

Nutrition

Calories: 103kcal | Carbohydrates: 5g | Protein: 6g | Fat: 6g | Saturated Fat: 3g | Cholesterol: 17mg | Sodium: 266mg | Potassium: 335mg | Fiber: 1g | Sugar: 2g | Vitamin A: 180IU | Vitamin C: 0.7mg | Calcium: 130mg | Iron: 0.4mg

Nutrition information is automatically calculated, so should only be used as an approximation.

Did you make this? Leave a comment below!
Close up photo of Chef Jessica Randhawa of The Forked Spoon in a blue spotted dress, in the sunlight

Jessica Randhawa

Chef | Food Photographer

Iโ€™m Chef Jessica Randhawa, bringing over 14 years of experience in creating and publishing over 1200 mouthwatering recipes, coupled with invaluable kitchen tips and professional guidance, to transform your daily cooking into a truly enriching culinary adventure.

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Recipe Rating




4.92 from 12 votes (9 ratings without comment)

6 Comments

  1. Sandra Hicks says:

    5 stars
    I’m curious to know why they turned out so watery. I don’t know what I could do different. After 20 minutes in the oven they were in about 1/8 in of water. So I tried to drain that but everything slipped off the caps. So I tried another batch same thing. This time I just took paper toweling and blotted the bottom.

    1. Jessica Randhawa says:

      Hi Sandra,

      It’s hard for me to say what happened, as I would have had to have been with you in the kitchen throughout the process.

  2. Karly says:

    5 stars

    These. Look. Amazing. Never thought I’d be sitting here drooling over mushrooms on a computer screen on a Monday morning, yet here I am. Doing that. I NEEEEED to try these immediately!

    1. Jessica Randhawa says:

      Hi Karly! Thank you ๐Ÿ™‚ I know, it’s pretty crazy how mushrooms can do that, right!? Love your site and recipes, btw. I’ve been a long-time follower of your site!

  3. cakespy says:

    5 stars

    I need to tell you that this recipe makes me want to challenge myself to see how many of them I can fit in my mouth at one time. AWESOME.

    1. Jessica Randhawa says:

      Bahahaha! That sounds hilarious and scary all at the same time.