Cut the ends off the courgettes. Cut in half lengthways, then slice thinly. Cut the halloumi into 1-2 cm cubes.
Put the courgette pieces, halloumi and tomatoes onto a large baking tray in a single layer. Drizzle over the olive oil and sprinkle over the oregano. Add a pinch of salt and pepper. Roast in the oven for up to 30 minutes, until the halloumi is turning golden.
Meanwhile, put a large pot of water on to boil and cook the pasta in it according to packet instructions.
Drain the pasta, reserving 200ml pasta water. Put the pasta and pasta water back in the empty pot. Add the halloumi and vegetables from the baking tray, and any juices from the tray. Mix well and serve.