Bring a large saucepan of salted water to the boil for the tortellini. Finely chop the onion, carrot and celery. Thinly slice the silverbeet stems, then coarsely chop the leaves. Crush or finely chop the garlic.
Step 2 — Start sauce
Heat 2 tsp olive oil in a medium deep frypan over medium-high heat. Cook the onion, carrot, celery, silverbeet stems and bacon, stirring occasionally, for 7 mins or until the vegetables are softened. Preheat the grill to high.
Step 3 — Simmer sauce
Add the garlic, Italian seasoning, tomato passata, 250ml (1 cup) water and 1 tsp umami seasoning* to the onion mixture and bring to a simmer. Reduce the heat to medium and cook for 8 mins or until slightly reduced. Stir in 1 tsp sugar. Taste, then season with salt and pepper.
Step 4 — Cook tortellini
Meanwhile, cook the tortellini in the pan of boiling water for 3 mins or until al dente. Put the silverbeet leaves in a colander. Drain the tortellini over the silverbeet leaves.
Step 5 — Add tortellini
Add the tortellini and silverbeet leaves to the sauce and gently toss to coat (handle the tortellini with care to ensure they don't break up or burst open).
Step 6 — Grill tortellini bake
Transfer the tortellini mixture to a 1.25L (5 cup) baking dish. Scatter over the cheese. Grill for 5-7 mins until the cheese is melted and golden. Serve the tortellini bake at the table for everyone to help themselves.