Portobello Mushrooms Stuffed with Creamy Mashed Potato Filling

These Stuffed Portobello Mushrooms are one of my favorite recipes. They pair roasted, savory portobello caps with rich, creamy mashed potatoes for a comforting, flavorful dish.

A  plate of vegetarian mashed potato stuffed mushrooms.

A quick look at this recipe

  • Recipe Name: Mashed Potato Stuffed Portobello Mushrooms
  • Ready In: 20 minutes prep, 35 minutes cook time
  • Serves: 6
  • Calories: 221 per serving
  • Main Ingredients: Portobello mushrooms, potatoes, butter, cream, Parmesan cheese
  • Difficulty: Easy

I love stuffed mushrooms for their simplicity and versatility. They’re easy to adapt and make ahead, and they work as a hearty vegetarian main or an elegant side.

I often make large batches of mashed potatoes for my personal chef clients, and stuffing them into meaty portobello caps is one of my favorite ways to change things up.

Roasting the mushrooms concentrates their flavor and adds a slight smokiness. Paired with mashed potatoes enriched with butter, sour cream, heavy cream and Parmesan, the result is decadent and satisfying.

These stuffed portobellos are so good they can easily steal the show at the dinner table.

Ingredients for stuffed portobello mushrooms

A board with potatoes, butter,, portobello mushrooms, heavy cream, Parmesan cheese.
  • portobello mushrooms
  • olive oil
  • kosher salt, pepper, garlic powder
  • potatoes — russet or Yukon Gold work well
  • salted butter, sour cream, heavy cream
  • Parmesan cheese
  • fresh parsley, scallions

See the recipe section below for exact measurements.

Substitutions and additions

  • Use high-starch potatoes like Russet or Yukon Gold for light, fluffy mashed potatoes.
  • Swap Parmesan with cheddar, Gruyère, Asiago or smoked Gouda for different flavor profiles.
A spoon being used to remove the gills from portobello mushrooms.

How to clean mushrooms for stuffed mushrooms

Mushrooms act like sponges, so avoid soaking them in water. A quick wipe with a dry paper towel removes surface dirt without adding moisture.

For stuffed portobellos, remove the stems and scrape out the dark gills under the cap. The gills can discolor the filling and make it look unappetizing. A spoon or grapefruit spoon works well to gently scrape them away.

Large mashed potato stuffed mushrooms on a baking sheet.

How do you make stuffed mushrooms not watery?

Nobody wants soggy stuffed mushrooms. Follow these tips for a dry, flavorful result:

  • Don’t wash mushrooms under running water; wipe them dry instead.
  • Roast the mushrooms before stuffing so excess moisture evaporates.
  • After roasting, pour off any liquid that accumulates on the baking sheet.

How to make stuffed mushrooms

These stuffed portobellos are simple to prepare and reheat well if you make them in advance.

Peeled potatoes, cubed potatoes and potato peels on a cutting board.
Adding heavy cream to partially mashed potatoes.
Stuffing roasted mushroom caps with mashed potatoes.
  1. Preheat the oven to 400°F (204°C).
  2. Clean the mushrooms with a paper towel, remove stems and scrape out the gills.
  3. Place mushrooms gill-side down on a rimmed baking sheet. Drizzle with olive oil and season with kosher salt, pepper and garlic powder. Roast 10–20 minutes, depending on size, until just tender. Remove and increase oven to 425°F (218°C).
  4. While mushrooms roast, peel and cut potatoes into 2-inch chunks. Cover with water in a large pot and simmer until tender. Drain and return potatoes to the pot.
  5. Add salted butter and mash. Stir in sour cream and heavy cream until smooth and creamy. Season with kosher salt and pepper, then fold in grated Parmesan.
  6. Flip roasted mushrooms over and drain any accumulated liquid from the baking sheet. Fill each cap generously with mashed potatoes and sprinkle with additional Parmesan.
  7. Return stuffed mushrooms to the oven and bake 10–15 minutes, until heated through and golden on top.
  8. Garnish with chopped fresh parsley and thinly sliced scallions before serving.
A meatless entree of a mashed potato stuffed portobello mushroom.

Amy’s cooking tips

  • Portobellos vary in size; smaller caps roast faster. Watch them so they become tender but still hold their shape.
  • Mash the potatoes while they’re hot for the creamiest texture; cooled potatoes can turn gluey.
  • Always drain any liquid from cooked mushrooms before stuffing to prevent a watery filling.
A bowl of grated parmesan cheese and 2 stuffed caps of mushrooms.

What to serve with stuffed portobellos

These mushrooms are flexible and pair well with many meals:

  • Serve as an elegant starter or first course for a dinner party.
  • Pair with a simple tossed salad for a light lunch.
  • Enjoy alongside roasted or pan-seared proteins for a full meal—mashed-potato-stuffed portobellos complement pork, chicken, fish or beef nicely.

One more thing

Photo of Amy Casey of amycaseycooks.com

Did you try this recipe?

Leave a comment and rating below to let me know how it turned out. Thanks — Amy

Recipe

Mashed Potato Stuffed Portobello Mushrooms

Roasted portobello caps filled with creamy Parmesan mashed potatoes — a hearty vegetarian main or a standout side dish.
5 from 5 votes
Prep Time: 20 minutes
Cook Time: 35 minutes
Total Time: 55 minutes
Servings: 6 servings
Calories: 221kcal
Author: Amy Casey

Ingredients

  • 6 portobello mushrooms
  • olive oil
  • kosher salt
  • pepper
  • garlic powder
  • 3 medium baking potatoes about 2 pounds
  • 3 tablespoons salted butter
  • 2 tablespoons sour cream
  • ¾ cup heavy cream
  • ½ cup grated Parmesan cheese plus more for sprinkling on top
  • 2 tablespoons chopped fresh parsley
  • 2 thinly sliced scallions green part only

Instructions

  • Preheat oven to 400°F (204°C).
  • Prep the mushrooms: gently brush off dirt, remove stems and scrape out the gills.
  • Place mushrooms gill-side down on a rimmed baking sheet. Drizzle with olive oil and season with kosher salt, pepper and garlic powder. Bake 10–20 minutes until just tender. Remove and increase oven to 425°F (218°C).
  • While mushrooms bake, peel and cut potatoes into 2-inch chunks. Cover with water in a large pot and bring to a boil, then reduce to a simmer until potatoes are easily pierced with a knife. Drain and return potatoes to the pot.
  • Add butter and mash. Stir in sour cream and heavy cream until smooth. Season with kosher salt and pepper, then add Parmesan and combine.
  • Flip mushrooms over, pour off any accumulated liquid, and fill each cap with mashed potatoes. Sprinkle with extra Parmesan.
  • Bake the stuffed mushrooms 10–15 minutes at 425°F (218°C), until hot and browned on top.
  • Remove from oven and garnish with parsley and scallions. Serve warm.

Notes

  • Portobellos vary in size; watch roasting times so they stay tender but intact.
  • Choose high-starch potatoes for the best texture.
  • Mash potatoes while hot for a creamy result.
  • Drain any liquid from cooked mushrooms before stuffing to prevent a soggy filling.

Nutrition

Serving: 1mushroom | Calories: 221kcal | Carbohydrates: 18.4g | Protein: 6.7g | Fat: 14.1g
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4 vegetarian stuffed mushrooms ready to be served.