1. Preheat your oven to 400°F (200°C).
2. In a large mixing bowl, combine the kielbasa slices and apple wedges.
3. Drizzle the olive oil over the kielbasa and apples. Add the brown sugar, Dijon mustard, dried thyme, salt, and pepper.
4. Toss everything together until the kielbasa and apples are evenly coated with the mixture.
5. Spread the mixture in a single layer on a baking sheet lined with parchment paper or a silicone baking mat.
6. Bake in the preheated oven for 20-25 minutes, or until the apples are tender and the kielbasa is nicely browned, stirring halfway through to ensure even cooking.
7. Remove from the oven and transfer to a serving dish. Garnish with chopped fresh parsley, if desired.
