Heat butter or oil in heavy saucepan. Add onions and garlic and cook for 5 min.
Add red crushed pepper and saute for 30 sec.
Add tomatoes. Simmer until the sauce is reduced and mash some of the tomatoes (~ 1 hour). In the meantime, you can start to prepare the filling and cook the shells.
Season with salt, pepper, and sugar to taste. Add fresh basil.
To Prepare Filling & Shells:
Combine vegan ricotta with chopped basil and chives. Season with salt and pepper to taste.
Cook shells al dente. Drain and rinse with cold water to stop cooking. Toss shells with some olive oil to avoid sticking (see notes below).
Spread prepared sauce over the bottom of two 9x13 glass baking dishes.
Fill 35 shells with vegan ricotta filling and divide them between the 2 dishes forming a single layer of jumbo shells.
Top with remaining sauce. Sprinkle on top with vegan feta (if using).
Bake for about 30 minutes at 350 degrees.
Remove and garnish with fresh basil. Serve hot with home-made garlic bread.
Gluten-Free Option - if you can't find gluten-free jumbo shells, you can use your gluten-free lasagna noodle and make a lasagna dish layering in the vegan ricotta and sauce.Cooking Jumbo Shells - make sure the shells are cooked al dente since they will be baked once again after being stuffed. After cooking, rinse with cool water, toss with a little olive oil, and try to go through to make sure they don't stick to each other.Vegan Ricotta Cheese - I use my homemade garlic & herb vegan ricotta, but you can also buy Kite Hill almond-based vegan ricotta. Vegan Feta Cheese - the only brand vegan feta that I've enjoyed is VioLife. You can easily omit the feta as well.