01 - Preheat your oven to 425°F (220°C). Line a large sheet pan with parchment paper or aluminum foil for easier cleanup.
02 - Arrange the cabbage wedges, apple wedges, and red onion wedges in an even layer on the prepared sheet pan.
03 - Place the sausages on top of the arranged vegetables and fruit.
04 - In a small mixing bowl, whisk together the maple syrup, mustard, olive oil, apple cider vinegar, salt, and black pepper until well combined.
05 - Evenly drizzle the prepared glaze over the sausages and vegetables. Gently toss everything on the pan to ensure an even coating, then arrange into a single layer.
06 - If using, sprinkle the fresh thyme leaves over the ingredients on the sheet pan.
07 - Roast for 25 to 30 minutes. Halfway through the roasting time, turn the sausages and stir the vegetables to ensure even cooking. Continue roasting until the sausages are nicely browned and cooked through, and the cabbage is tender and caramelized.
08 - Serve the dish hot, spooning any accumulated pan juices over the top for added flavor.