Melt butter in a skillet over medium heat. Once fully melted and starting to bubble slightly, add the minced red onion. Sauté for about 2 minutes until the onions become fragrant and translucent but not browned.

Add the chopped parsley and minced garlic to the onions, stirring to combine. Pour in the lemon juice and sprinkle in the red pepper flakes. Mix everything together for about 30 seconds until the garlic becomes aromatic.

Pour in the chicken stock, then gradually add the Parmesan cheese while stirring constantly. Once incorporated, pour in the heavy cream and stir until you have a smooth, creamy sauce that coats the back of a spoon.

Bring the sauce to a gentle simmer for about 1 minute, then turn off the heat. Allow it to cool for 3-4 minutes while you prepare the chicken.

Season the chicken pieces with salt, smoked paprika, and chicken seasoning in a large bowl. Toss well to ensure every piece is evenly coated. Arrange the seasoned chicken in a single layer in a 9x13 inch baking dish and pour the cooled sauce over top, making sure each piece gets coated.

Bake uncovered at 375°F for 1 hour and 45 minutes, flipping the chicken pieces after 50 minutes for even cooking. The chicken is done when the meat pulls away from the bone easily and reaches an internal temperature of 165°F.

Turn your broiler to high and broil the chicken on the skin side until golden brown and slightly crispy, watching carefully to prevent burning. Use a spoon to drizzle the pan sauce over each piece before serving.