Melt the Butter: Set a large pot over medium heat. Add butter and let it melt fully. Swirl it around so it coats the bottom evenly.
Cook the Chicken: Add chicken cubes to the pot. Stir and cook until the outside turns white and lightly golden. This step builds flavor early.
Add the Mushrooms: Stir mushrooms into the pot. Let them cook until soft and slightly darker. They release moisture and deepen the taste.
Sprinkle the Flour: Shake flour evenly over the chicken and mushrooms. Stir well so no dry spots remain. This thickens the sauce later.
Pour in Liquids: Slowly add chicken broth while stirring. Follow with milk and keep stirring until smooth. The mixture should look creamy.
Add Pasta and Seasoning: Place spaghetti into the pot and press it down gently. Sprinkle salt, pepper, and garlic powder over the top.
Simmer Until Tender: Cover the pot and let everything cook on low heat. Stir occasionally so pasta stays loose. Cook until noodles turn soft.
Finish with Cheese: Turn off the heat and stir in Parmesan cheese. Sprinkle parsley on top and mix gently before serving.
