Season the chicken with the Italian seasoning, paprika, onion powder, salt, and black pepper.
Heat the olive oil in a large skillet over medium-high heat.
Add the chicken and cook for 6–8 minutes, stirring occasionally, until golden brown and cooked through. Transfer the chicken to a plate.
Reduce the heat to medium and add the butter to the same skillet.
Stir in the minced garlic and cook for 30 seconds, until fragrant.
Add the zucchini (and any optional vegetables) and cook for 4–5 minutes, stirring occasionally, until crisp-tender.
Return the cooked chicken to the skillet and toss everything together.
Sprinkle the Parmesan cheese over the mixture and stir until melted and evenly coated.
Add the lemon juice, if using, and garnish with fresh parsley.
Serve immediately while hot.