Preheat the oven to 400°F (200°C).
In a large oven-safe skillet, heat the olive oil over medium heat.
Add the sliced onions and garlic to the skillet, cooking until they are soft.
Stir in the diced sweet potatoes and season with salt, pepper, and thyme.
Arrange the chicken thighs and apple sausage on top of the sweet potatoes.
Add the sliced bell pepper on top, then transfer the skillet to the preheated oven.
Bake for 25–30 minutes or until the chicken reaches an internal temperature of 165°F (74°C).
Remove from the oven and let it rest for 5 minutes before serving.
Serve warm, garnished with fresh herbs if desired.