Preheat oven to 350ºF. Spray 2 ½ quart casserole dish with nonstick spray. Set aside.
Cut chicken breasts in half. Lightly brown chicken breasts seasoned with salt and pepper in 1 tablespoon of butter, about 3 minutes per side. Set aside. (See Tip 2)
Cook broccoli in boiling salted water for 5 minutes. Drain and add to ice water to stop the cooking. Drain well; set aside. (See Tip 3)
To prepare cream sauce, heat the remaining 3 tablespoons of butter in a saucepan over medium heat. Add flour, and cook for 2 minutes over medium heat, ensuring that the flour does not brown. Gradually add milk, whisking or stirring constantly. Cook and whisk until the mixture comes to a boil and is thickened and smooth. Add 1 teaspoon of salt, ¼ teaspoon of pepper, and 2 tablespoons of sour cream. Whisk until well combined.
Arrange broccoli, with the florets facing out in the prepared casserole dish. Place chicken in the center of the casserole dish. Pour sauce evenly over the chicken. Sprinkle with Parmesan cheese and paprika. (See Tip 4)
Bake at 350ºF for 30 minutes or until bubbly. Serve with yellow rice and green peas, crusty French bread, and chilled white wine such as Chenin blanc or chardonnay. Yield: 4 servings. (See Tip 4)