Heat the olive oil in a large skillet over medium-high heat.
Add the onion and cook for 3 to 4 minutes until softened.
Stir in the garlic and cook for 30 seconds until fragrant.
Add the ground chicken and cook for 6 to 8 minutes, breaking it apart until browned and fully cooked.
Stir in the bell pepper, zucchini, and broccoli. Cook for 5 to 6 minutes until the vegetables begin to soften.
Add the Italian seasoning, garlic powder, paprika, salt, and black pepper. Stir well to coat the chicken and vegetables.
Mix in the tomato paste and chicken broth, then simmer for 2 to 3 minutes.
Stir in the butter until melted and combined.
Sprinkle the mozzarella cheese over the skillet if using, cover for 2 minutes until melted, then garnish with fresh parsley before serving.