Preheat the oven to 350°F.
Cook the tortellini according to package directions. Drain well and set aside.
Slice the andouille sausage into rounds. Slice the onions and bell peppers.
Spread the sausage, onions, and bell peppers on a large sheet pan. Drizzle generously with olive oil and season with Creole seasoning, salt, and pepper. Toss to coat evenly.
Add the drained tortellini to the pan and toss everything together so the tortellini is coated in the olive oil and seasoning alongside the vegetables and sausage.
Spread into as even a single layer as possible. Bake at 350°F for 30 minutes until the vegetables are tender, the sausage is slightly caramelized, and the tortellini has developed slightly golden, crisped edges.
Serve directly from the sheet pan.