Add crushed and diced tomatoes. Simmer 20-30 minutes.
14.5 ounces can diced tomatoes, 28 ounces can crushed tomatoes
While the marinara sauce simmers prepare the manicotti shells. Add the shells to a large rectangular pan and fill it with hot tap water, as hot as you can make it. Let the shells soak for 20-30 minutes.
1 package manicotti shells
Mix ricotta cheese, egg, and 1/2 cup of the Parmesan cheese in a bowl. Cut the fresh basil and blend in with ricotta mixture.
Scoop half the sauce into bottom of cast iron skillet or rectangular baking pan.
Fill the shells with ricotta mixture and place in skillet. Put the filling in a ziploc bag, cut the corner off and use the bag to pipe filling into the shells. It is easiest to fill one half, then turn the shell and fill the other half.
Cover the stuffed manicotti shells with the remaining sauce. Top with shredded mozzarella and the remaining ¼ cup parmesan.
8 ounces mozzarella cheese
Bake at 350° for 55-60 minutes or until cheese is starting to turn golden brown.
Notes
You can make up to a day ahead of time and refrigerate, tightly covered, until ready to bake.