In a medium saucepan, boil cashews in water for 20 minutes until soft, then rinse them with cold water or soak them overnight.
In a food processor, add water, olive oil, lemon juice, nutritional yeast, salt and garlic, and process until smooth. Set aside.
Preheat oven to 375° F and line two baking sheets with parchment paper.
In a small bowl, add cauliflower, 2 teaspoons olive oil, salt and garlic powder. Mix well and spread the coated florets in an even layer on the baking sheet. Roast for 15 minutes per side. When done, remove from oven and set aside.
Brush the caps and the bottoms of the mushrooms with remaining 1 olive oil and place them on the second baking sheet. Roast them for 10 minutes on each side. Cool for a few minutes then slice in strips with a pairing knife. Set aside.
In a 9 x 13 casserole dish, evenly spread 3/4 cup of marinara sauce, then layer the butternut squash on top. Layer 1 cup of the cashew ricotta cheese, roasted cauliflower, and portobello mushrooms over the butternut squash, and spread 1 cup of sauce over the top. Repeat by layering the butternut squash, cashew ricotta cheese, and marinara sauce until the ingredients are gone.
Cover with foil and bake for 20 minutes. The outside should be bubbly and the squash should be starting to soften. (Check by inserting a knife through the center of the dish.) Remove the aluminum foil and continue baking the dish for 20 minutes.
If desired for a non-vegan option, sprinkle mozzarella or Parmesan cheese on top after 15 minutes, and cook until cheese is melted. Serve warm.
Serving size: 1 serving, Calories: 415 calories, Fat: 28 grams, Saturated fat: 5 grams, Carbohydrates: 30 grams, Sugar: 12 grams, Sodium: 115 milligrams, Fiber: 5 grams, Protein: 13 grams, Cholesterol: 0 milligrams