Heat marinara sauce in a large, wide pot over medium heat. Cover to prevent splattering.
Remove crusts from bread, place bread in a medium bowl and pour water over. Let sit 10 minutes, and gently squeeze out excess liquid. Put bread in a large bowl; discard water.
Add the ground turkey, cheese, egg, onion, parsley, basil, oregano, salt and red pepper flakes to bowl with bread. Gently toss to combine, maintaining a light touch to keep air in the meatballs (don't squish the meat too much, or you'll end up with tough meatballs). Roll the meat mixture in your hands to create meatballs slightly larger than a golf ball.
Remove marinara sauce from heat to prevent splattering, and gently drop the meatballs in the warm sauce. Return tomato sauce to medium-low heat, bring to a simmer and cook, covered, until meatballs have cooked through, about 30 minutes.
Cook pasta according to package directions, toss with marinara sauce and top with meatballs.
Make your own marinara: Heat 1 tablespoon olive oil and saute 2 cloves minced garlic until lightly golden. Add 32 ounces of canned, peeled, crushed plum tomatoes and simmer for 10 minutes. Add meatballs and 2 tablespoons of torn fresh basil leaves, and season with 1 1/2 teaspoons salt and 1/2 teaspoon pepper. Cook for 30 minutes.