In a large measuring cup with a spout, combine the gravy packet with 1 cup of cold water, stirring until fully blended. Incorporate the tomato sauce and seasonings, then set the mixture aside.

Cube the chicken into evenly sized pieces, seasoning them with salt and pepper. Dust with flour and toss to coat thoroughly.

In a large skillet, heat olive oil over medium-high heat. Add the chicken and sear for 3-4 minutes until golden brown. Flip the pieces and continue cooking on all sides until fully cooked, approximately 3 more minutes. Remove the chicken from the skillet and set it aside.

Turn off the heat, then add 1/4 cup of the chicken broth and set the burner to medium. Using a silicone spatula, scrape the bottom and sides of the skillet to incorporate any browned bits, enhancing the flavor of the sauce.

Next, add the butter and sliced onions. Cook over medium heat, stirring frequently, until the onions are very soft and nearly caramelized, which should take about 20 minutes.

Stir in the garlic and cook for an additional minute.

Pour in the remaining chicken broth and let it simmer gently for 5 minutes to reduce slightly.

Next, add the gravy mixture prepared earlier to the skillet. Increase the heat to bring it to a boil, allowing it to thicken for about 30 seconds. Then, reduce the heat to a simmer and return the chicken to the skillet.

Partially cover the skillet while you bring a pot of water to a boil for the spaghetti. Once the water is boiling, add salt (approximately 1/4 tablespoon). Cook the spaghetti until it reaches al dente, then drain it.

Add the cooked spaghetti to the sauce and toss well to ensure it's evenly coated. Garnish with parsley and serve alongside Garlic Bread with Cheese!