3 Carnival, Dumpling or acorn squashes, cut in half lengthwise and seeded (each 1 1/4 to 1 1/2 pounds)
2 tablespoons olive oil
2 small onion, cut into approximately 1/4-inch dice (8 ounces)
1 small red bell pepper, cut into approximately 1/4-inch dice (5 ounces)
Freshly ground black pepper
2 medium zucchinis, cut into approximately 1/4-inch dice (8 ounces)
8 ounces white or cremini mushrooms, cut into approximately 1/4-inch dice
1 large egg, lightly beaten
1 1/2 cups part-skim ricotta
6 tablespoons grated Parmesan cheese
2 tablespoons finely chopped parsley
Freshly ground nutmeg
INSTRUCTIONS: Preheat the oven to 350 degrees. Arrange the squash halves, cut side down, in one layer in a deep roasting pan. Add water to the pan to a depth of 1/2 inch. Cover the pan with aluminum foil and bake until the squash flesh is just tender, 45 to 60 minutes.
Carefully transfer the squash halves to a work surface and turn them cut side up. Allow them to cool for 10 minutes, then scoop out a total of about 2 cups of flesh from the halves, making sure to leave a layer of flesh so the halves hold their shape. Mash or chop the squash meat to break up any clumps.
While the squash is cooling, line a large rimmed baking sheet or a roasting pan with aluminum foil and spray with nonstick cooking oil spray.
Heat the oil in a large nonstick saute pan or skillet over medium-high heat. Add the onion and bell pepper, and season with salt and pepper to taste. Cook for 5 to 6 minutes, stirring occasionally, until the onion is soft. Add the zucchini and mushrooms; cook for about 8 minutes, stirring occasionally, until the vegetables are soft and just starting to brown a little. Add the squash flesh, and stir to combine well. Cook for 3 to 4 minutes, stirring, to allow the excess moisture from the squash to evaporate. Remove from the heat.
Mix the egg, ricotta, 4 tablespoons of the Parmesan cheese and the parsley in a large bowl. Season with salt, pepper and nutmeg to taste. Add the cooked vegetable mixture and stir to combine.
Place the cooked squash halves, skin side down, in the prepared pan. Fill each half with an equal portion of the ricotta-vegetable mixture. Sprinkle each with an equal portion of the remaining 2 tablespoons of Parmesan. Bake for 30 to 35 minutes, until the filling is set and the edges are just starting to brown. Let the squashes rest for at least 30 minutes before serving. Reheat in a 350-degree oven if they have cooled too much. If the squashes have been refrigerated, cover with aluminum foil while reheating.