Yes, I can substitute pappardelle for fettuccine. Pappardelle is a wide, flat noodle, while fettuccine is a long, thin noodle. Both are made with eggs, and both can be used in similar dishes. Pappardelle is typically used in hearty meat sauces, while fettuccine is often used in lighter cream sauces. Either pasta would be delicious in this dish!