Preheat oven to 400°F (200°C). Cut spaghetti squash in half lengthwise and scoop out seeds.
Drizzle spaghetti squash halves with olive oil and season with salt and pepper.
Place squash halves cut-side down on a baking sheet and roast for 30-35 minutes until tender.
While squash roasts, season chicken breasts with salt, pepper, garlic powder, onion powder, and Italian seasoning.
Heat olive oil in a large skillet over medium heat and cook chicken breasts 5-7 minutes per side until cooked through.
Remove chicken from skillet and set aside to rest, then slice into strips.
In the same skillet, melt butter and sauté minced garlic until fragrant.
Add cream cheese, Parmesan cheese, almond milk, and nutmeg, stirring constantly until smooth and creamy.
Use a fork to scrape spaghetti squash strands into a bowl once cooked.
Combine spaghetti squash strands with Alfredo sauce and sliced chicken, stirring gently to coat.
Serve garnished with fresh parsley or basil.