Preheat the oven to 400 F.
Place the sliced sausages in a large bowl.
Add the cubed potatoes, diced bell pepper, and red onion.
Mix the smoked paprika, red pepper flakes, salt, and pepper in a small bowl. Sprinkle over the veggies and sausages. Drizzle with olive oil, and toss to coat completely.
Line a baking sheet with aluminum foil or parchment paper. Transfer the sausage, bell peppers, onion, and potatoes to the prepared baking sheet. Bake for 20 minutes. Remove from the oven, and add the minced garlic and dried thyme; stir. Return to the oven and bake for 15-20 minutes or until golden brown. Top with shredded white cheddar cheese and bake for 2-3 minutes or until the cheese melts. Garnish with fresh thyme or chopped flat-leaf/curly parsley. Serve warm.