In a large skillet, melt the butter over medium heat. Add the diced onion, green bell pepper, and sliced mushrooms. Sauté for about 5-7 minutes, or until the vegetables are tender.
Stir in the flour, garlic powder, paprika, salt, and pepper. Cook for 1-2 minutes to create a roux.
Gradually whisk in the chicken broth and heavy cream, stirring continuously until the mixture thickens, about 3-5 minutes.
Add the cooked chicken and frozen peas to the skillet. Stir to combine and heat through, about 2-3 minutes.
Serve the chicken mixture over cooked rice or egg noodles. Garnish with chopped fresh parsley if desired.