Step 1: Season the Chicken - Start by preheating your oven to 375 degrees and setting a 9 by 13 baking dish aside. In a large bowl, add your chicken breasts along with the salt, pepper, and onion powder. Take a minute here to really coat each piece well. You want that seasoning spread evenly so every bite has flavor. This step sets the foundation for the whole dish, so do not rush it.
Step 2: Sear for Flavor - Heat the vegetable oil in a large skillet over medium to high heat. Once the oil is hot, add the chicken breasts. Let them cook for about three minutes on each side until they develop a nice golden color. You are not cooking them all the way through here, just building that crust. That golden sear adds a deeper flavor that really makes a difference once everything bakes together.
Step 3: Mix the Creamy Sauce - While the chicken is searing, grab a small bowl and combine the sour cream with the onion soup mix. Stir it until smooth and fully blended. It will look thick and creamy, and that is exactly what you want. This sauce is going to melt down in the oven and coat the chicken in all that rich flavor.
Step 4: Assemble the Dish - Place the seared chicken breasts into your prepared baking dish. Spoon the sour cream mixture over each piece, spreading it out so everything is covered. Do not worry about being perfect here, just make sure each piece gets a good layer. Then sprinkle the shredded cheddar cheese evenly over the top. This is where things start to look really good.
Step 5: Bake Until Tender - Cover the baking dish with foil and place it in the oven. Let it bake for 25 minutes so the chicken can cook through and soak up all that flavor. After that, remove the foil and bake for another 5 minutes. This final step helps the cheese melt beautifully and gives the top a slightly golden finish.
Step 6: Finish and Serve - Carefully remove the dish from the oven and let it sit for a couple of minutes. If you are using parsley, sprinkle it over the top for a fresh touch. When serving, do yourself a favor and spoon some of that extra sauce from the bottom of the dish right over the chicken. That is where all the flavor lives.