- Preheat oven 200°C/Fan 180°C/Gas Mark 6
- Place vegetables and onion on a roasting tray, add garlic, olive oil, seasoning and sprinkling of herbs. mix well, then roast for 45 mins, turning occasionally. Remove from oven and stir in tomatoes.
- Place the butter and flour in saucepan, heat gently, slowly add milk and stir continuously until sauce thickens, mix in 100g cheese, mustard powder, seasoning and remove from heat.
- Using a large ovenproof dish, spoon half vegetable mix into dish, place a layer of lasagne sheets on top, repeat with vegetable mix finishing with layer of lasagne sheets. Pour over cheese sauce, sprinkle with remaining cheese.
- Bake for 40-45 minutes until golden brown, cover with foil if necessary if the top is getting too brown.