Preheat oven to 400°F (200°C). Mix ground chicken, egg, panko, Parmesan, olive oil, garlic powder, onion powder, salt, and pepper until just combined. Roll into 1-inch meatballs and place on a baking sheet.
Bake meatballs for 25-30 minutes until cooked through and browned. Set aside.
Cook spaghetti according to package directions until al dente. Reserve 1/2 cup pasta water, then drain pasta.
Melt butter in a large pot over medium heat. Add minced garlic and sauté until fragrant.
Add spinach and parsley to the pot. Cook until spinach is wilted.
Add cooked spaghetti, meatballs, and reserved pasta water to the pot. Toss to combine, adding more pasta water as needed for a creamy sauce. Season to taste.