Heat olive oil in a large skillet over medium heat.
Season the chicken thighs with salt and pepper, then add them to the skillet.
Remove the chicken from the skillet and set aside.
Add the sliced apple sausage and diced onion to the skillet.
Sauté for about 5 minutes until the onions are translucent.
Add the Brussels sprouts, garlic, and thyme to the skillet.
Stir to combine and cook for another 3-4 minutes.
Add the sliced apples back into the skillet.
Return the chicken thighs to the skillet, nestling them among the other ingredients.
Cover and cook for an additional 10-15 minutes until the chicken reaches an internal temperature of 165°F.