Preheat the oven to 200C, fan-forced. Bring a medium saucepan of salted water to the boil for the pasta. Wipe the mushrooms clean, then thinly slice. Thinly slice the onion. Coarsely grate the cheese. Cut the chicken into 2cm chunks.
Step 2 — Cook pasta
Add the pasta to the pan of boiling water and cook, stirring occasionally, for 8-9 mins until the pasta is almost al dente (the pasta will cook further in the oven). Reserve 2 tbs cooking water, then drain the pasta. Rinse under hot water to prevent the pasta from sticking.
Step 3 — Brown chicken
While the pasta is cooking, heat 1 tbs olive oil in a medium frypan over medium-high heat. Add the chicken, season with salt and cook, stirring, for 3 mins or until browned.
Step 4 — Soften vegetables
Add the mushrooms and onion to the chicken and cook, stirring occasionally, for 5 mins or until the vegetables are softened and the chicken is cooked through.
Step 5 — Bake pasta
Add three-quarters of the cream*, 3 tsp pepper and garlic seasoning* (see cooking tip) and reserved cooking water to the chicken mixture and stir to combine. Bring to a simmer, then stir in pasta. Taste, then season with salt. Transfer pasta mixture to a 1.5L (6 cup) ovenproof dish and scatter with cheese. Bake for 8-10 mins until pasta is al dente and top is golden.
Step 6 — Dress rocket and serve
Meanwhile, combine 2 tsp extra virgin olive oil and 2 tsp white wine vinegar in a large bowl and season with salt and pepper. Add the rocket and toss to coat. Take the pasta bake to the table and serve with the dressed rocket.