Bring a medium saucepan of salted water to the boil for the pasta. Thinly slice the zucchini. Combine 2 tbs white wine vinegar and 2 tsp sugar in a small saucepan and bring to a simmer over medium-high heat. Add the zucchini and cook, covered, for 3-4 mins until softened. Remove the pan from the heat and set aside, covered, to pickle.
Step 2 — Cook pasta
Cook the pasta in the pan of boiling water for 10 mins or until al dente. Reserve 60ml (¼ cup) cooking water, then drain the pasta.
Step 3 — Brown beef
Meanwhile, preheat the grill to high. Thinly slice the onion. Coarsely grate the cheese. Heat 2 tsp olive oil in a medium deep ovenproof frypan (see Kitchen notes) over high heat. Cook the beef mince and onion, breaking up the lumps with a spoon, for 3-4 mins until browned.
Step 4 — Add pasta
Add the barbecue seasoning, tomato paste and 1 tsp dijon mustard to the beef mixture. Reduce the heat to medium and cook, stirring, for 1 min or until combined. Add the pasta and reserved cooking water and cook, stirring, for 1 min or until combined and the sauce is slightly thickened. Remove from the heat. Taste, then season with salt and pepper.
Step 5 — Grill and serve up
Scatter the cheese over the pasta mixture and grill for 5 mins or until melted and golden. Divide the pasta bake among plates or pop the dish on the table for everyone to help themselves. Serve with the drained pickles and enjoy!
Step 6 — Kitchen notes
Your frypan will need an ovenproof handle to cook under the grill. If you don't have one, wrap the handle of a regular frypan with a double layer of foil, or transfer the pasta mixture to an ovenproof dish before adding the cheese and grilling in Step 5.