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Roasted flat mushrooms with green onion thyme b 2026 01 12 155602 819x1024

Roasted Flat Mushrooms with Green Onion, Thyme & Butter

A delightful dish that highlights the rich flavor of mushrooms combined with fresh herbs and creamy butter. Perfect for weeknight dinners or special gatherings.
Prep Time 5 minutes
Cook Time 25 minutes
Total Time 30 minutes
Course Appetizer, Side Dish
Cuisine American
Servings 8 servings
Calories 120 kcal

Ingredients
  

Mushrooms

  • 8 large large flat mushrooms (portobello, around 10 – 12 cm / 4 – 4.5" wide, stem tips trimmed)

Butter and Seasoning

  • 100 g unsalted butter (softened) About 7 tablespoons
  • 1 cup green onion (thinly sliced)
  • cup parsley (finely chopped)
  • 1 tbsp fresh thyme leaves (or 1 tsp dried)
  • ½ tsp salt
  • ¼ tsp black pepper
  • 3 tbsp chopped scallions

Garnish

  • 1 dozen thyme stalks

Instructions
 

Preparation

  • Start by cleaning the mushrooms as per Note 1.
  • Preheat your oven to 200°C (390°F) or 180°C (fan).
  • In a medium bowl, mix together the softened butter, green onions, parsley, thyme, salt, and pepper.

Baking

  • Place the mushrooms gills side up on a large tray. Use the butter mixture to smear over the surfaces of the mushrooms.
  • Cover the tray with foil to keep the herbs green.
  • Bake in the oven for about 25 minutes, or until the mushrooms are tender.

Serving

  • Arrange the mushrooms on a platter, pouring any leftover butter and juices from the tray over them.
  • Scatter with thyme stalks and extra scallions for a fresh touch before serving.

Notes

Ensure mushrooms are cleaned gently to avoid using too much water, which can make them soggy. You can adjust the herbs according to your preference. For a vegan option, substitute the butter with plant-based margarine. For a variation, consider adding cheese on top of the mushrooms before baking.
Keyword Butter, Green Onion, Mushrooms, Roasted Mushrooms, Thyme