Step 1

Heat oven to 160C/140C fan/gas Put the potatoes in a large roasting tin with the onion. Pour over 2 tbsp olive oil and roast in the oven for about 30 mins.

Step 2

Add the chickpeas, pepper, romanesco, tomatoes and garlic. Drizzle with 2 tbsp oil, then roast for a further 20-25 mins until everything is cooked and browning nicely. Toss together briefly and put the halloumi slices on top. Put it under the grill for 5-10 mins, or until the cheese is melting and browning (keep an eye on it). Scatter over the basil leaves to serve.