Zucchini and Spinach Gratin with Ricotta Custard

My adaptation of a recipe from Deborah Madison's Book The Savory Way takes advantage of dried zucchini and frozen spinach from the garden. A pound of fresh zucchini dries down to about 1 ounce. I rehydrated it with the liquid that the frozen zucchini gives off as well as the moisture from the mushrooms and onions. The vegetable mixture should be prepared in advance to allow the zucchini to absorb the moisture from the other vegetables. It can be mixed and kept in the refrigerator overnight or longer.

1.25 ounces (35 g.) dried sliced Romanesco zucchini
8 ounces frozen spinach, thawed, excess moisture squeezed out and reserved
2 tablespoons olive oil
1 medium onion, chopped
2 cloves garlic, minced
1/4 pound mushrooms, thinly sliced
1 tablespoon tomato paste thinned with a little water
sweet fermented pepper flakes to taste (optional)
1 tablespoon chopped parsley
crumbled dried oregano to taste

1 cup ricotta cheese
2 eggs
1 cup milk, cream or a combination
1/2 cup freshly grated Parmesan cheese
salt
freshly ground pepper
freshly grated nutmeg

Place the dried zucchini in a bowl. Add the reserved spinach water to the zucchini and set aside.

Warm the oil in a medium skillet and add the onions and garlic. Sauté about 1 minute, then add the mushrooms and a pinch of salt. Cook until the mushrooms soften and begin to release their liquid. Transfer the mixture to the bowl of zucchini, stir to mix, cover and set aside for a few hours or overnight in the fridge.

Preheat the oven to 350ºF.

Season the rehydrated zucchini mixture with the tomato paste, pepper flakes, parsley, oregano, and salt and pepper to taste. Transfer the mixture to a gratin dish. Chop the spinach and distribute it over the zucchini mixture, season with salt and fresh ground pepper.

Beat the ricotta with the eggs, then stir in the milk or cream, the cheese, and the remaining parsley. Season with salt and nutmeg. Pour the mixture over the vegetables. Bake until the custard is set and lightly browned on top, about 40 to 45 minutes. Allow the gratin to stand about 10 minutes before serving. Serve warm.

Makes 4 main course servings.