Dried porcini and fresh cremini mushrooms give this baked stuffed zucchini recipe heartiness that's rarely found in vegetable side dishes. Pair this Zucchini Ripiene al Forno with grilled chicken or pork for a delicious Italian dinner.
Place mushrooms in a medium bowl. Pour 2 cups boiling water over mushrooms; let stand for 15 minutes. Drain, discarding water. Coarsely chop soaked mushrooms; set aside.
Preheat oven to 350°F. Meanwhile, in a medium skillet cook bread crumbs in 3 tablespoons of the hot butter about 3 minutes or just until beginning to turn golden brown. Stir in one clove of the minced garlic; cook and stir about 1 minute more or until garlic is fragrant. Remove from heat; stir in parsley. Season with 1/4 teaspoon of the salt and the pepper; set aside.
Trim ends of three of the zucchini; cut each of these zucchini in half lengthwise. Using a melon baller or a small measuring spoon, scoop out and reserve pulp, leaving 1/4-inch-thick shells. Coarsely chop pulp and the one remaining zucchini; set aside.
For sauce, in a small saucepan melt 4 tablespoons of the remaining butter over medium heat. Stir in flour. Stir in milk. Cook and stir over medium heat until thickened and bubbly. Cook and stir for 1 minute more. Reduce heat to low. Stir in Parmesan cheese and 1/4 teaspoon of the remaining salt. Set aside.
For filling, in medium skillet melt the remaining 1 tablespoon butter over medium heat. Add the chopped zucchini, chopped soaked mushrooms, fresh mushrooms, and onion; cook about 5 minutes or until onion is tender. Stir in thyme, the remaining two cloves garlic, and the remaining 1/4 teaspoon salt. Cook and stir for 30 seconds. Remove from heat. Stir in 2/3 cup of the bread crumb mixture.
Spread sauce in a 3-quart rectangular baking dish. Place filled zucchini shells on top of the sauce. Sprinkle with the remaining bread crumb mixture. Bake, covered, for 30 minutes. Uncover. Bake about 10 minutes more or until sauce is bubbling and zucchini are tender when pierced with the tip of a small knife. Serve hot or warm.