Preheat the oven to: 180°C / Fan 170°C / Gas Mark 4

Heat the oil in the roaster; add the onion and some seasoning. Cook over a low heat, stirring occasionally, for 10 minutes until the onion is soft and translucent. Add the tomatoes and simmer for a further 10 minutes, until the juices have reduced and thickened slightly. Adjust the seasoning to taste.

Drain the jar of peppers well. Chop the flesh into small pieces. Put the ricotta cheese into a mixing bowl and stir in the Parmesan cheese, chopped red peppers, marjoram, parsley, beaten egg and some salt and pepper into a bowl, mix well.

Bring a large pan of salted water to the boil. Drop 10 of the lasagne sheets into the boiling water, one at a time and cook for 5 minutes, stirring occasionally to ensure that they don't stick together. Remove with a slotted spoon to a bowl of cold water, then lift out and lay side by side on a clean tea towel to drain. Repeat with the remaining lasagne sheets.

Spoon some of the ricotta mixture along the short edge of each sheet of lasagne, roll them up and lay them side by side, in two long rows over the top of the tomato sauce.

For the cheese sauce place the butter, flour and milk into a large saucepan. Heat, whisking constantly, until the mixture boils and thickens. Add the nutmeg and season well.Pour the sauce over the cannelloni, covering them completely and sprinkle the Parmesan cheese over the top.

Cook in the centre of the oven for 30-40 minutes, until bubbling hot and the top is golden brown.

Serve with a crisp green salad and crusty bread.