Preheat the oven to 400 degrees F. Position an oven rack in the middle of the oven.
Melt the butter in a large oven-proof skillet over medium heat. Add the onions. Season with salt and pepper. Cook, stirring frequently, until the onions are translucent and very soft, about 5 minutes. Add the sausage and cook until hot. Mix in the corn, heavy cream, Parmesan and garlic powder.
Place the chicken thighs skin-side up on top of the corn mixture. Drizzle the chicken skin with some oil and sprinkle with salt and pepper. Place the skillet on the middle rack of the oven and bake until the chicken is brown and crispy, 30 to 35 minutes.
Remove from the oven and let the chicken rest for 5 or 10 minutes. Serve with rice.