Bring a large pot of salted water to a boil. Add tortellini and cook for 3–5 minutes, or until tender and floating. Drain and set aside, tossing lightly with olive oil to prevent sticking.
In a bowl, season chicken pieces with Cajun seasoning, salt, pepper, and garlic powder. Heat olive oil in a large skillet over medium-high heat. Add the chicken and sear for 5–6 minutes until golden and cooked through. Remove from skillet and set aside.
In the same skillet, melt butter. Add diced bell pepper and sauté for 3–4 minutes until softened. Add garlic and cook for another minute. Stir in spinach (if using) and cook until wilted.
Pour in heavy cream and milk (or chicken broth). Simmer for 2–3 minutes until it begins to thicken. Add Parmesan and mozzarella cheeses, stirring until smooth. Adjust seasoning with extra Cajun spice or red pepper flakes.
Add the cooked chicken and tortellini back into the skillet. Stir gently until evenly coated in sauce. Simmer for 1–2 minutes to combine flavors.
Sprinkle with fresh parsley, extra Parmesan, and black pepper. Serve hot directly from the skillet.
