Baked Pesto-Stuffed Portobello Mushrooms with Mozzarella

Why You’ll Love This Recipe

• Comforting, cheesy stuffed mushrooms balanced by a bright, lemony quinoa salad.
• Weeknight-friendly: under 1 hour with plenty of overlap while the mushrooms bake.
• Vegetarian and naturally gluten-free with easy dairy-free swaps.
• Great for entertaining—eye-catching, deeply flavorful, and easy to scale.

Grocery List

• Produce: 4 large portobello caps, fresh basil, flat-leaf parsley, 1 lemon, 1 cucumber, 1 small red onion, 1–2 ripe plum tomatoes, 1 pint cherry tomatoes, 1 garlic clove
• Dairy: Low-moisture mozzarella, Parmesan (for pesto), optional feta for the salad
• Pantry: Quinoa, extra-virgin olive oil, Dijon mustard, honey or maple syrup, pine nuts or walnuts, kosher salt, black pepper, optional balsamic glaze

Full Ingredients

For the pesto-stuffed mushrooms

• 4 large portobello mushroom caps (4–5 inches wide), stems and gills removed
• 1 tbsp olive oil (for brushing)
• 1/2 tsp kosher salt
• 1/4 tsp freshly ground black pepper
• 2/3 cup herbed pesto (homemade, below, or store-bought)
• 1/2 cup finely diced plum tomato, seeds removed and patted dry
• 1 cup shredded low-moisture mozzarella (about 4 oz)
• Optional: 1 tbsp grated Parmesan and/or a drizzle of balsamic glaze for serving

Quick herbed pesto (yields about 2/3 cup)

• 2 cups packed fresh basil leaves (about 50 g)
• 1/2 cup loosely packed flat-leaf parsley leaves
• 1 small garlic clove
• 3 tbsp toasted pine nuts or walnuts
• 1/3 cup finely grated Parmesan
• 1/4 cup extra-virgin olive oil
• 2 tbsp cold water
• 1 tbsp fresh lemon juice
• 1/4 tsp kosher salt, plus a pinch of black pepper

Lemony quinoa salad

• 1 cup dry quinoa, rinsed well
• 2 cups low-sodium vegetable broth or water
• 1 cup cherry tomatoes, halved
• 1 cup diced cucumber (seeded if watery)
• 1/4 small red onion, finely minced (about 2 tbsp)
• 2 tbsp chopped fresh parsley
• 2 tbsp extra-virgin olive oil
• 2 tbsp fresh lemon juice
• 1 tsp Dijon mustard
• 1/2 tsp honey or maple syrup
• 1/2 tsp kosher salt, 1/4 tsp black pepper (adjust to taste)
• Optional: 1/4 cup chopped fresh basil; 1/4 cup crumbled feta (about 1 oz)

To serve

• Fresh basil leaves and a few toasted pine nuts for garnish (optional)

Step-by-Step Instructions

Step 1: Preheat and set up the pan

Heat the oven to 400°F (200°C). Line a rimmed baking sheet with foil for easy cleanup and set a wire rack on top if you have one. Elevating the mushrooms helps excess moisture drip away so the caps roast rather than steam.

Step 2: Clean and pre-bake the portobellos

Use a spoon to gently scrape out the black gills and remove the stems. Brush both sides of each cap with 1 tablespoon olive oil total, then season evenly with 1/2 teaspoon kosher salt and 1/4 teaspoon black pepper. Arrange gill-side up on the rack or sheet pan and bake for 8 minutes. Carefully pour off any liquid that collects in the caps and on the pan.

Step 3: Make the herbed pesto

In a food processor, combine basil, parsley, garlic, nuts, and Parmesan. Pulse until finely chopped. With the machine running, stream in 1/4 cup olive oil, then add 2 tablespoons cold water and 1 tablespoon lemon juice. Season with 1/4 teaspoon salt and a pinch of pepper. The pesto should be spreadable; add a splash more water if needed. Alternatively, use 2/3 cup good-quality store-bought pesto.

Step 4: Prep the tomato and assemble the caps

Seed and finely dice a plum tomato, then pat the pieces dry with a paper towel to prevent watery mushrooms. Spread 2 to 3 tablespoons pesto into each pre-baked cap. Scatter about 2 tablespoons diced tomato over each, then cover with 1/4 cup shredded mozzarella. Sprinkle on 1 tablespoon grated Parmesan if using.

Step 5: Bake until tender and melty

Return the stuffed mushrooms to the oven and bake for 10 to 12 minutes, until the cheese is melted and the caps are tender but still hold their shape. For extra color, switch to broil and brown the tops for 1 to 2 minutes, watching closely. If you like, finish with a light drizzle of balsamic glaze.

Step 6: Cook the quinoa while mushrooms bake

Bring 2 cups broth or water to a boil in a medium saucepan. Stir in the rinsed quinoa, reduce heat to low, cover, and simmer for 15 minutes. Remove from heat and let rest, covered, for 5 minutes. Uncover and fluff with a fork.

Step 7: Make the lemony salad and serve

In a large bowl, whisk 2 tablespoons olive oil, 2 tablespoons lemon juice, 1 teaspoon Dijon, and 1/2 teaspoon honey with 1/2 teaspoon salt and 1/4 teaspoon pepper. Add the warm quinoa, cherry tomatoes, cucumber, red onion, and parsley; toss to coat. Taste and adjust seasoning. Plate a mound of quinoa salad with a pesto-stuffed portobello on top or alongside. Garnish with fresh basil and toasted pine nuts if desired.

Pro Tips

• Drain the pre-bake juices: tipping off moisture after the first bake keeps the caps meaty, not soggy.
• Use low-moisture mozzarella for best browning and minimal water release.
• Pat the diced tomato dry to prevent pooling inside the caps.
• A wire rack over your sheet pan helps air circulate and prevents steaming.
• Let quinoa rest before fluffing for the lightest texture.

Variations

• Dairy-free/vegan: Use vegan pesto (no Parmesan) and dairy-free mozzarella; add nutritional yeast for cheesy depth.
• Mediterranean twist: Add 2 tbsp chopped sun-dried tomatoes to the pesto and a handful of sliced olives to the quinoa salad.
• Protein boost: Fold 1 cup drained, rinsed white beans into the quinoa salad.

Storage & Make-Ahead

Pesto can be made 3 days ahead; store refrigerated in a jar with a thin layer of olive oil on top. Quinoa salad keeps well for up to 3 days; toss with the dressing just before serving if you prefer it less absorbed. Clean and pre-bake the mushroom caps up to 1 day in advance; cool, cover, and refrigerate. Stuff and finish baking just before serving. Leftover cooked stuffed mushrooms keep 2–3 days in the refrigerator; reheat at 350°F (175°C) for 10–12 minutes or in the microwave in short bursts. Freezing is not recommended.

Nutrition (per serving)

Approx. 600 calories; 23 g protein; 45 g carbohydrates; 32 g fat; 6 g fiber; 830 mg sodium. Nutrition will vary with ingredient brands and optional add-ins.