Cook pasta: Boil the fusilli in salted water until al dente, then drain and place in a large bowl.
Prepare chicken: Season the chicken breasts with garlic powder, salt, and pepper, then cook in olive oil until golden. Let them rest before cutting into pieces.
Create dressing: Whisk together olive oil, vinegar, Italian seasoning, minced garlic, and dijon mustard. Season with salt and pepper to your liking.
Assemble salad: Toss the pasta with chicken, bacon, tomatoes, spinach, feta, onion, and dill. Drizzle with dressing and toss until everything is well coated.