Make the Sauce: In the same skillet, melt 4 tbsp butter over medium heat. Add the chopped onion and sauté until softened. Stir in the diced tomatoes and minced garlic. Sauté for about 30 seconds. Sprinkle in 1 tbsp flour and stir to combine. Add the red pepper flakes and 1 tsp Italian seasoning. Gradually whisk in 1 cup heavy whipping cream and ½ cup grated Parmesan cheese. Continue to sauté until the sauce thickens.
Combine and Serve: Stir the cooked spaghetti into the sauce. Add the cooked chicken back into the skillet. Toss everything to combine and heat through.
Prep Time: 15 mins | Total Time: 35 mins | Servings: 4
