Twice Baked Gruyere and Potato Souffle

Directions

1. Preheat oven to 400°F. Peel the potatoes and cook in lightly salted, boiling water for 20 minutes, until very tender. Drain well and mash with egg yolks, using a potato masher or a fork.
2. Stir in half of the Gruyere cheese and all of the flour. Season to taste with salt and ground black pepper.
3. Grease four large ramekins; set aside. Finely chop the spinach and fold into the potato mixture.
4. In a clean, grease-free bowl, whisk the egg whites until they form soft peaks.
5. Fold a little of the egg white into the potato mixture to loosen it slightly, then fold the remaining egg white into the mixture using a large spoon.
6. Pour the mixture into the ramekins and place them on a baking sheet. Bake for 20 minutes, then remove the ramekins from the oven and leave to cool.
7. Turn the soufflés out on to a baking sheet and sprinkle with the remaining cheese. Bake again for 5 minutes and serve immediately.