Cut bread into 2cm cubes. Place cubed bread into a baking tray and drizzle with olive oil. Bake in oven for about 45 minutes. Once they are crunchy and golden, remove from oven and set aside.
Roughly chop onion and leeks. Finely chop garlic cloves. Heat olive oil in a pan over medium heat. Add onions, leeks and garlic cloves and allow to simmer for 10 minutes – keeping lid on and stirring occasionally. Season with 1 tsp salt and 1 tsp pepper.
Chop wood sorrel and beetroot leaves. Stir into pot and then simmer for 30 minutes on low heat with a lid. After 30 minutes uncover the pot and raise the temperature to medium high. Add lemon juice, nutmeg and salt and pepper to taste.
Heat milk in a small pot, allowing to simmer but not boil.
Grease a casserole dish. Place ⅓ of the bread cubes in dish, topping with ½ the green stew, and then topping with another ⅓ of the bread, adding the last ½ of the stew, and adding the final layer of bread to the top. Pour the warmed milk over the dish, moistening all the ingredients. Sprinkle the gruyere cheese evening over the top of the dish. Cover casserole with foil before placing into oven. Bake for 1 ¾ hours.
After 1 ¾ hours, raise the temperature to 200deg, and remove foil. Bake for a further 20 minutes.
Recipe adapted from original, “The Slow Mediterranean Kitchen” by Paula Wolfert.