This recipe is one of those cozy, feel-good meals that looks fancy but is super easy to make.
The mushrooms turn soft and juicy, the veggies stay colorful and fresh, and the walnuts bring the perfect little crunch.
I love how hearty it feels without needing any meat, and the balsamic glaze ties it all together with a sweet and tangy kick.
Why I Love This Recipe
I’ve been making this for years when I want something comforting but not too heavy. It started as a way to use up leftover veggies, but quickly became a go-to dish I crave. The mushrooms soak up all that flavor, and the balsamic glaze? So good.
- It’s completely plant-based, but still super satisfying
- It’s easy to prep ahead
- You can switch up the filling with whatever you’ve got
- Great for dinner parties or a cozy solo meal
Servings & Time
Servings: 4
Total time: 35 minutes (15 min prep + 20 min cook)
Macros (per serving – approximate)
- Calories: 220
- Protein: 6g
- Carbs: 18g
- Fat: 14g
- Fiber: 5g
What You’ll Need
- 4 large portobello mushrooms (stems removed, wiped clean)
- 1 tablespoon olive oil
- ½ red onion, finely diced
- 1 red bell pepper, diced
- 1 yellow bell pepper, diced
- 2 cups fresh spinach, roughly chopped
- ½ teaspoon salt
- ¼ teaspoon black pepper
- ½ teaspoon garlic powder
- ¼ cup chopped walnuts
- 2 tablespoons balsamic glaze
- 1 tablespoon chopped fresh parsley (for garnish)
Ingredients Flat Lay
Tools You’ll Need
- Baking sheet
- Parchment paper
- Small sauté pan
- Mixing spoon
- Knife + cutting board
- Small bowl (for glaze)
- Oven mitts
Pro Tips
- Don’t rinse mushrooms under water — just wipe with a damp towel so they don’t get soggy.
- Scoop out a little of the inside of the mushroom cap for more filling space.
- Use pre-chopped veggies to save time.
- Toast the walnuts for extra crunch and flavor.
- Let the mushrooms rest 5 minutes after baking so they’re easier to serve.
Substitutions & Variations
- No spinach? Use kale or chopped zucchini.
- Swap walnuts with pecans or sunflower seeds.
- Add some crumbled feta or vegan cheese on top before baking.
- Use pre-made balsamic glaze or reduce your own.
Make Ahead Tips
You can prep the veggie filling and clean the mushrooms a day ahead. Store them separately in the fridge and stuff + bake the next day.
Instructions
Step 1: Preheat the Oven
Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.
Step 2: Prep the Mushrooms
Gently wipe 4 large portobello mushrooms with a damp cloth. Remove the stems and use a spoon to scrape out the gills to make space for the filling.
Step 3: Sauté the Veggies
Heat 1 tablespoon olive oil in a small pan over medium heat. Add ½ diced red onion, 1 diced red bell pepper, and 1 diced yellow bell pepper. Cook for 4-5 minutes until soft.
Step 4: Add Spinach & Seasonings
Add 2 cups chopped fresh spinach, ½ teaspoon salt, ¼ teaspoon black pepper, and ½ teaspoon garlic powder to the pan. Stir for another 2-3 minutes until the spinach wilts.
Step 5: Mix in the Walnuts
Turn off the heat. Stir in ¼ cup chopped walnuts to the warm veggie mix.
Step 6: Fill the Mushrooms
Place the cleaned mushroom caps on the lined baking sheet, gill-side up. Spoon the veggie-walnut filling evenly into each cap.
Step 7: Bake
Bake the stuffed mushrooms at 400°F (200°C) for 20 minutes, until the mushrooms are tender and the tops are golden.
Step 8: Drizzle with Balsamic Glaze & Serve
Remove from oven, drizzle 2 tablespoons balsamic glaze over the tops, and sprinkle with chopped parsley. Serve warm on a plate.
Why This Recipe Works (Quick Science)
Mushrooms are like flavor sponges — they soak up all the juices and seasonings. When roasted, they release moisture, making them tender and meaty. The high heat also caramelizes the veggie sugars, bringing out natural sweetness. Walnuts add crunch and healthy fats, while balsamic glaze balances it all with tang and sweetness.
Common Mistakes
- Washing mushrooms under water – They’ll get soggy. Just wipe them clean.
- Overcrowding the pan – Sauté veggies in a single layer so they cook evenly.
- Undercooking the mushrooms – You want them soft and juicy, not raw.
- Not seasoning enough – Salt brings out the flavor in both mushrooms and veggies.
What to Serve With
- Garlic bread or warm baguette
- Quinoa or couscous salad
- A simple green salad with lemon vinaigrette
- Roasted sweet potatoes
Leftovers & Storage
Store leftovers in an airtight container in the fridge for up to 3 days. Reheat in the oven at 350°F (175°C) for 10–12 minutes. Avoid microwaving—they get soggy.
FAQ
Can I use smaller mushrooms?
Yes, baby bellas work great as appetizers—just reduce the cooking time to 12–15 minutes.
Is this gluten-free?
Yes! Just double-check your balsamic glaze brand to be sure.
Can I freeze these?
I don’t recommend freezing—they get mushy. Better to prep ahead and bake fresh.
Conclusion
These stuffed portobello mushrooms are a simple, satisfying recipe you’ll want to make again and again. Perfect for a light dinner, a meatless main, or an impressive side. Try it out and leave a comment letting me know how it turned out—or if you put your own twist on it!