Cook the manicotti tubes in boiling salted water per the package instructions until al dente. (around 7 minutes) Remove to paper towels to cool slightly.

Meanwhile, drizzle a large skillet with olive oil. Add the chopped onion. Cook for 3 minutes over medium-high heat until beginning to brown then add the garlic. Cook for 1 minute longer.

Add the Italian sausage to the skillet. Cook for 10-12 minutes or until no pink remains, Drain any excess fat from the pan.

To the cooked sausage add the cream cheese, Italian seasoning, garlic salt, black pepper, crushed red pepper flakes and Worcestershire sauce. Cook over medium heat just until the cream cheese melts and is evenly distributed.

Remove from the heat and stir in 1 1/2 cup mozzarella cheese, 4 Tbsp Parmesan and chopped basil. Mix well.

Use a pair of kitchen shears and cut each manicotti shell in a straight line. Fill with 2 heaping Tbsp filling down the middle, then press the ends together to seal. Place seam side down in the dish. Repeat filling all of the shells.

Cover the top with the remaining 2 cups marinara sauce, spread to cover.

Cover the manicotti with aluminum foil and bake for 30 minutes. Uncover and sprinkle with the remaining mozzarella cheese and 2 Tbsp Parmesan.

Return to the oven and cook for an additional 15-20 minutes until golden and bubbly.

Rest for 5 minutes on the counter then serve.