Can I use cooked pasta instead of uncooked manicotti?
Yes, but reduce water to 1/4 cup and baking time to 25-30 minutes, since cooked pasta won't need softening in the sauce.
Can I substitute the chicken sausage?
Pork Italian sausage works equally well; use the same amount and break it into smaller pieces if needed.
How do I know when the manicotti is done?
The pasta shells should be tender when pierced with a fork and the sauce should be bubbling around the edges after 45-50 minutes at 375°F.
Can I make this ahead?
Yes, assemble completely, cover, and refrigerate up to 24 hours; add 10-15 minutes to baking time when cooking from cold.
What if I don't have string cheese?
Use 1/2 cup shredded mozzarella mixed into the filling, or omit entirely if preferred—the dish will still be creamy from the Alfredo sauce.