Heat the olive oil in a large skillet over medium-high heat.
Season the chicken pieces with salt, black pepper, and garlic powder.
Add the chicken to the skillet and cook for 5-7 minutes, stirring occasionally, until browned and cooked through. Remove the chicken from the skillet and set aside.
In the same skillet, add the diced onion and cook for 2-3 minutes until softened.
Add the minced garlic, red bell pepper, zucchini, and mushrooms to the skillet. Cook for 5-6 minutes, stirring occasionally, until the vegetables are tender.
Return the cooked chicken to the skillet with the vegetables.
Pour in the chicken broth and bring to a simmer. Let it cook for 3 minutes to reduce slightly.
Reduce the heat to medium-low and stir in the heavy cream, Parmesan cheese, dried Italian seasoning, and crushed red pepper flakes.
Cook for another 5 minutes, stirring occasionally, until the sauce thickens and coats the chicken and vegetables.
Add the baby spinach leaves and cook for 1-2 minutes until wilted.
Taste and adjust seasoning with additional salt and pepper if desired.
Serve the creamy chicken and vegetable skillet hot.