Preheat oven to 350 degrees Fahrenheit.
If making homemade ricotta, pesto, parmesan and /or marinara, refer to the recipes linked below and create these first.
In a large pasta pot, bring water to a boil. When it's boiling add 1-2 tablespoons salt. Then add approximately 20- 22 jumbo shells and cook according to the directions on the box for an al dente finish. Do not overcook or they will be hard to fill. They will continue to cook in the oven.
While the pasta is cooking, spread a layer of marinara sauce on the bottom of a 7 x 11-inch (or similar size) casserole dish.
Drain the pasta well after cooking, then add it to the casserole dish lined with the marinara sauce.
Then line the inside of a large cup with a pastry or Ziploc bag. Fill the bag with the vegan ricotta mixture. Trim off 1/2- 3/4 inch of the bag's tip. Gently squeeze the ricotta down to the tip's opening. Insert the tip into the first pasta shell and squeeze the ricotta until the shell is full. Continue with the rest of the pasta.
When all the shells are full, top with the marinara sauce, making sure to cover all the shells well so that no pasta shows through.
Cook in a preheated oven for 30-40 minutes until bubbly. Remove from oven and top with parmesan.