Preheat oven to 400 degrees F.
Place halved Brussels sprouts, diced sweet potatoes, diced onions, and cranberries in a large bowl. Add the olive oil, garlic powder, salt, and pepper and mix well to coat.
Transfer to a baking sheet lined with parchment paper or aluminum foil and spread in an even layer.
Roast in a preheated oven for 30-45 minutes total, stirring every 10-15 minutes with a spatula.
While the veggies are roasting, add the Dijon mustard, balsamic vinegar, honey, thyme, and salt into a jar or container with a lid and shake well. About 10 minutes before the veggies are done roasting, add the honey mustard glaze, tossing to coat, then return to the oven to finish.
Once the veggies are dark golden brown, remove from the oven, sprinkle with feta cheese and serve immediately. Enjoy!