2. Into a powerful blender add the cashew pieces together with 3/4 cups of water, juice from 1 lemon, grated garlic, onion powder and sea salt. Process until smooth and creamy. Transfer the mixture to a bowl, cover and refrigerate until needed.
3. Bring a large pot of water to a boil. Season generously with a large pinch of coarse salt then cook the pasta according to the directions on the package until al dente in texture.
4. Prepare a bowl of ice cold water. Use a slotted spoon and transfer the cooked pasta shells to the bowl of cold water to stop the cooking process. Drain and transfer to a large bowl. Drizzle with a light drizzle of olive oil to prevent sticking.
6. Using a regular teaspoon fill each pasta shell with the cashew ricotta. Place in the dish with the sauce. You can line them up straight or at an angle if desired. Repeat the process until all the shells are filled. Sprinkle with the red pepper flakes at this point if desired.
7. Spoon the remaining of the sauce over the top of the shells and spread as evenly as you can. Cover with aluminum foil and bake in the preheated oven for 30 minutes.