Mushroom Wellington Recipe: How to Make Mushroom Wellington

For the mushroom duxelles:

• 3 tablespoons olive oil
• 1 pound mixed mushrooms (such as oyster, chestnut, shiitake, or cremini), finely diced
• 6 garlic cloves, finely chopped or pulsed in a food processor
• 1 teaspoon fresh thyme leaves, finely chopped
• 1 teaspoon fresh rosemary leaves, finely chopped
• 2 tablespoons soy sauce
• Kosher salt
• Freshly ground black pepper

For the caramelized onions:

• 3 tablespoons butter
• 3 red onions, thinly sliced
• 1 teaspoon kosher salt
• ⅓ cup dry white wine
• 7 ounces baby spinach, roughly chopped

For the assembly:

• 4 large Portobello mushroom caps
• 4 tablespoons grapeseed oil, divided
• 1 tablespoon Dijon mustard
• 1 9.6-ounce sheet puff pastry, thawed if frozen
• 2 egg yolks, beaten
• 2 fresh thyme sprigs

1. 1

   Preheat the oven to 450 degrees Fahrenheit with a rack in the center.

2. 2

   Make mushroom duxelles. Place a large sauté pan over medium high heat. Add oil and when hot, add mushrooms. Add the garlic, soy sauce, thyme and rosemary. Stirring frequently to be sure mushrooms don’t stick, cook until all moisture has evaporated, about 15 minutes.

3. 3

   Transfer to a bowl and allow to cool. Wipe out the pan.

4. 4

   Make the caramelized onions. Place the same sauté pan over medium heat. Add butter and when melted, add onions and 1 teaspoon salt. Cook, stirring occasionally, until onions are softened and translucent, about 5 minutes.

5. 5

   Add the wine and continue cooking until onions are deep golden brown and the wine evaporates, about 10–12 minutes.

6. 6

   Stir in spinach until wilted and water evaporates, about 5 minutes.

7. 7

   Season to taste with salt and pepper.

8. 8

   Transfer to a bowl and allow to cool. Wipe out the pan.

9. 9

   Trim rims of mushroom caps and any remaining stem so that the stem side is flat. Brush mushrooms with 2 tablespoons of grapeseed oil and season with salt and pepper.

10. 10

    Place the same sauté pan over medium high heat and add the remaining oil. Once the pan is hot, sear the mushrooms, cooking 3–4 minutes per side.

11. 11

    Remove mushrooms to a sheet tray. While hot, brush Dijon mustard all over.

12. 12

    Line a baking sheet with parchment paper.

13. 13

    Place the sheet of puff pastry in the center, then use a rolling pin or dowel to evenly roll it to ⅛-inch thick.

14. 14

    Turn the cutting board so the long side of the puff pastry rectangle is closest. Spread half of the mushroom duxelles in a vertical 4-inch wide rectangular strip in the center of the puff pastry with a 2-inch border at the top and bottom.

15. 15

    Top with caramelized onions and spinach in an even layer over the mushroom duxelles.

16. 16

    Layer the portobello mushrooms over the onions in a single layer, then spread the pastry with the remaining mushroom duxelles.

17. 17

    Fold one long pastry side over the mushroom filling. Brush with egg yolk wash and season with salt and pepper.

18. 18

    Fold the other side of the pastry over the filling. Lightly brush the pastry and the insides of the short puff pastry ends with egg wash, and press to tightly seal.

19. 19

    Use a sharp knife to gently score the top of the puff pastry and create a decorative pattern.

20. 20

    Season with more salt and pepper, and top with thyme sprigs.

21. 21

    Place the baking tray in the center of the oven and bake for 40–45 minutes, until golden brown.

22. 22

    Remove and let rest for 5 minutes before slicing and serving.

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