Preheat the oven to 400°F.
In a large 9x11 glass baking dish, toss grape tomatoes, quartered baby potatoes, bell peppers, and red onion with one tablespoon olive oil and chopped garlic.
Add salt, pepper, and Italian seasoning. Mix well.
Place the sausage links on top of the vegetables. Cover with foil and bake for 60 minutes.
Remove the sausage bake from the oven. Then, remove the tinfoil from baking dish, mix vegetables around, and bake for an additional 30 minutes until sausage is golden brown. (*You may need to turn the sausage to prevent from burning). Serve immediately.