Italians serve this festive dish for holidays and special occasions. As with lasagna, most of the preparation can be done up to a day ahead. Tomato sauce or concentrate in a tube imported from Italy will help you achieve the naturally sweet taste of a good ragu. If theyre unavailable, a touch of sugar or herbs, such as sweet basil or bay leaf, added to the sauce during cooking will reduce the acidity of American tomato products. Soy cheese does not reheat well, so if youre using it, bake this dish just before youre ready to serve it. Do not use fat-free cheese because it turns rubbery when melted. When cooking the soy sausage, be sure to use a nonstick pan.
Ragu: In medium nonstick skillet, heat 2 tablespoons of oil over medium-high heat. Add soy sausage and cook until well browned, breaking up with wooden spoon or plastic spatula, about 8 minutes. Set aside. In small, heavy, dry skillet, heat bread crumbs over medium heat, stirring constantly, until lightly browned. Mix in 2 teaspoons of oil and continue stirring until mixture is crisp, brown and fluffy. Set aside to cool in pan.
In 3-quart Dutch oven or deep saucepan, heat remaining 2 tablespoons oil over medium-high heat. Add onion and cook, stirring often, until softened, about 3 minutes. Stir in garlic and cook until onion is tender, about 3 minutes. Stir in tomato sauce, tomato concentrate, cooked sausage and pepper flakes and bring to boil. Reduce heat to low and simmer, stirring occasionally, until sauce thickens, 15 to 20 minutes. Remove from heat. Blend in miso by mashing it against side of pot with back of wooden spoon. Season with salt and pepper.
Cook pasta in large pot of lightly salted boiling water until just tender. Meanwhile, preheat oven to 400°F. Spray 13 x 9-inch ovenproof dish with cooking spray. Drain pasta thoroughly.
To assemble, cover bottom of prepared baking dish with a third of ragu. Spoon half of pasta over sauce. Scatter half of pepperoni if desired and half of peas over pasta. Cover with another third of ragu. Repeat, using remaining pasta, pepperoni and peas. Cover with remaining ragu. Top with cheese and sprinkle with bread crumb mixture. Cover pan with foil. (The assembled dish can stand at room temperature for 1 to 2 hours before baking.)
Bake until bubbling and heated through, 30 to 35 minutes. Remove foil and let stand for 10 minutes before serving.