Potato, Leek and Kale Gratin with Crunchy Almond Rosemary Crust

Instructions

1. 1

   Preheat the oven to 200 °C / 400 °F. Lightly grease a baking dish about 9 x 7 inches with a little butter.

2. 2

   Heat the olive oil and butter in a large skillet over medium heat. Add the leek with a pinch of salt and cook for 4 to 5 minutes until tender. Stir in the garlic and cook for 30 seconds.

3. 3

   Add the chopped kale to the skillet and cook for 2 to 3 minutes, stirring, until slightly wilted. Remove from the heat.

4. 4

   In a jug or bowl, whisk together the heavy cream, milk, Dijon mustard, nutmeg, half of the Gruyère, half of the Parmesan, the remaining salt, and the black pepper.

5. 5

   Arrange one-third of the sliced potatoes in the baking dish, slightly overlapping. Spread one-third of the leek and kale mixture over them. Repeat 2 more layers until all the potatoes and vegetables are used.

6. 6

   Pour the cream and cheese mixture evenly over the dish, making sure it seeps into the layers. Cover the dish with aluminum foil.

7. 7

   Bake for 30 minutes at 200 °C / 400 °F.

8. 8

   Meanwhile, combine the sliced almonds, fresh rosemary, the remaining Gruyère, and the remaining Parmesan in a bowl.

9. 9

   Carefully remove the foil, scatter the almond rosemary topping over the surface, and bake again for 12 to 15 minutes at 200 °C / 400 °F, until the potatoes are tender when pierced and the crust is golden and crisp.

10. 10

    Let the gratin rest for 8 to 10 minutes before serving so the sauce can settle.