Mix the apples, onions, applesauce, cinnamon, and thyme in the dish and season with salt and pepper.
Pierce the sausages several times with a fork and place on top of the apple and onion mixture.
Bake in a preheated oven at 220°C (428°F) on the middle rack for 45 minutes, until the sausages are golden brown and reach an internal temperature of 63°C (145°F).