Wipe the mushrooms clean, then thinly slice. Finely chop the onion. Crush or finely chop the garlic. Strip the rosemary leaves, discarding the tough stems. Reserve half the rosemary leaves and finely chop the remainder. Finely grate the parmesan. Bring a large saucepan of salted water to the boil for the tortellini.
Step 2 — Start sauce
Heat 1 tbs olive oil in a medium deep frypan over high heat. Cook the mushrooms, onion, garlic, chopped rosemary and Italian seasoning, stirring occasionally, for 4 mins or until the mushrooms are golden. Season with salt and pepper.
Step 3 — Simmer sauce
Add the tomatoes, half the tomato paste*, 125ml (½ cup) water and 1 tsp sugar to the mushroom mixture and bring to a simmer. Reduce the heat to medium and cook for 6 mins or until slightly reduced. Stir in half the cream* and cook for a further 2 mins or until the sauce is slightly reduced. Taste, then season with salt and pepper.
Step 4 — Fry rosemary
Meanwhile, heat 2 tsp olive oil in a small frypan over high heat until hot. Cook the reserved rosemary leaves for 10-30 secs until crisp. Drain on paper towel.
Step 5 — Cook tortellini
Cook the tortellini in the pan of boiling water for 3 mins or until al dente. Drain.
Step 6 — Get ready to serve
Add the tortellini and half the parmesan to the sauce and gently toss to coat (handle the tortellini with care to ensure they don't break up or burst open). Divide the wagyu beef tortellini among bowls. Scatter with the remaining parmesan and crisp rosemary to serve.