Recipe Courtesy of the Mushroom Council and Le Delicieux
Yield: 3-4 servings
6 portabella mushrooms, stalks trimmed and cleaned
3 onions, peeled and chopped
2 tablespoons of olive oil
2 tablespoons of butter
100g of baby spinach
4 sprigs of thyme
1 sheet of frozen puff pastry, partially thawed
1 egg, beaten
1 tablespoon of dijon mustard
salt and pepper to taste
1. Preheat the oven to 200 degrees Celsius (390 Fahrenheit) and place a large frying pan over a medium heat and add the olive oil. When the pan has come up to heat add the onion and reduce heat to low. Season with salt and pepper and cook for 15 to 20 minutes, stirring occasionally. When caramelised, remove the onions from the pan and set aside.
2. Return the pan to the heat and add the baby spinach and cook until wilted. Remove from the baby spinach from the pan and set aside.
3. Return the pan to the heat again and increase heat to medium. Add the butter and when the butter has melted and started to froth add the mushrooms, top side down, season with salt and pepper, and cook for a 5 minutes or until golden, before turning over. Once both sides have been browned remove from the heat and brush both sides of the mushrooms with the dijon mustard.
4. Place a sheet of baking paper on the baking tray and then place the puff pastry sheet on top. Spread the caramelised onions over the middle third of the pastry, making sure to leave 1 to 2cm at the edges. Top with half the baby spinach and then the mushrooms. Top the mushrooms with the remaining baby spinach.
5. Very carefully roll the pastry over the top of the mushroom mixture until you have a log. Tuck the edges under the pastry, ensuring the seam is facing the bottom.
6. Cut 2 holes in the middle of the pastry to allow steam to escape and very lightly coat with the egg wash. Then place the pastry in the freezer for 10 minutes before repeating with another layer of egg wash and freezing the pastry for 10 minutes.
7. Place the pastry back on the baking sheet and tray and place in the oven for 30 to 35 minutes, or until golden.