In a large pot, bring water, olive oil and 2 teaspoon of salt to a boil. Add manicotti shells. Pot should be large enough to allow manicotti shells plenty of room to move while boiling. Boil for 6 minutes only. Gently remove pasta from pot with tongs or large spoon. Place in a single layer on wax paper. Do not drain in colander. Pasta should be al dente.
In a medium bowl, mix together Ricotta, 1 ½ C Mozarella, ¼ C Parmesan and beaten egg. Stir in parsley, lemon juice, salt, pepper and garlic. Spoon mixture into piping bag or large zip top bag and snip off the corner.
Spread ½ of pasta sauce in the bottom of a 9x13 or large casserole dish. Using the piping bag, fill each manicotti shell with cheese mixture and place side by side in casserole dish. Pour remaining sauce over the manicotti. Top with rest of cheese. Bake for 30-35 minutes.
Garnish with a sprinkle of extra parsley before serving, if desired.
Notes
Instead of parsley, use fresh basil in the summer for a delicious dish that's perfect for dining al fresco!