01 - Preheat oven to 425°F. Line a large sheet pan with parchment paper or aluminum foil for easy cleanup.
02 - Scatter sliced cabbage, apples, and red onion evenly across the prepared sheet pan.
03 - Place sausages on top of the arranged vegetables and fruit.
04 - In a mixing bowl, whisk together maple syrup, mustard, olive oil, apple cider vinegar, salt, and pepper until emulsified.
05 - Drizzle the glaze over sausages and vegetables. Toss gently to ensure even coating, then arrange in a single layer.
06 - Sprinkle thyme leaves evenly over the sheet pan contents.
07 - Roast for 25–30 minutes, turning sausages and stirring vegetables halfway through. Continue roasting until sausages are browned and cooked through, and cabbage is tender and caramelized.
08 - Transfer to plates and spoon any pan juices over the top. Serve immediately.