Preheat oven to 375 degrees. Bake sweet potatoes until soft, about 45 minutes. When potatoes are tender, remove to a bowl and mash. Set aside.Place broccoli, cauliflower, leeks, bell peppers, Herbes de Provence, and no-salt seasoning blend in a large saute pan along with 2 cups of water. Simmer until almost tender, about 10 minutes. (If using frozen broccoli and cauliflower, reduce water to 1 1/2 cups.) Add spinach and toss.Drain and remove vegetables, reserving vegetable liquid in pot. Whisk cornstarch into carrot juice and whisk into boiling vegetable liquid until it thickens. Add vegetables and crumbled tofu to sauce and toss to combine.Divide mixture into two 8-inch pie pans. Top each with 1/4 cup nuts. Spread sweet potatoes over the top and sprinkle with remaining nuts.Bake for 20-30 minutes until hot and nuts are lightly brown. Sprinkle with parsley, and serve.Note: This dish may be prepared ahead and frozen, unbaked. Cover tightly with aluminum foil before freezing. Do not defrost before baking, and bake an additional 10 to 15 minutes.