Spinach Bread & Butter Casserole (from Jenna)

SPINACH BREAD AND BUTTER CASSEROLE (from Vegetarian and Vegetable Cooking, serves 4 to 6)(I know that it doesn't sound great, but trust me! It's good)

Ingredients:
1 lb spinach (either fresh leaf, in which case you need to blanch it for just two minutes or frozen... in both cases you want to squeeze out the excess water before you begin)
1 ciabatta loaf (or any firm baked bread, we use the local farmer's bread)
4 Tbs. softened butter, margarine or olive oil (I generally use Smart Balance spread)
1 red onion, thinly sliced
4 ounces mushrooms, thinly sliced (fresh or canned)
2 Tbs. Olive oil
1 tsp. cumin seed
salt and pepper
4 ounces Gruyere Cheese, grated (you can substitute swiss- we have b/c it's cheaper... but the Gruyere is really good!)
3 eggs
2 1/4 cup milk
grated fresh nutmeg

1. After blanching (or defrosting) your spinach, squeeze out excess water and chop roughly.
2. Spread the butter over the bread slices thinly. Grease a large shallow ovenproof dish and line the bottom and sides with bread.
3. Fry the onion and mushrooms lightly in the oil for five minutes, then add the cumin seeds and spinach. Season well.
4. Layer the spinach mixture with the remaining bread and half the cheese. For the top, mix everything together and sprinkle the remaining cheese on top.
5. Beat the eggs with the milk, adding seasoning and nutmeg to taste. Pour slowly over the whole dish and set aside for at least an hour to let the custard be absorbed into the bread. (I always let it set in the fridge)
6. Preheat the oven to 375 degrees. Cover the dish (we've actually covered it and not, as well as followed the directions and put it in a roasting pan with boiling water around it... it's good any way) and bake for 40-45 minutes, until risen, golden brown and crispy on top.