Ingredients
Roulade:
1 tbsp oil
1 onion, finely chopped
2 cloves garlic, crushed
225g/8oz carrots, fine grated
225g/8oz courgettes, medium grated
good pinch of fresh chopped sage
110g/4oz cheddar cheese, grated
50g/2oz sesame seeds
6 eggs, separated
Sauce:
55g/2oz butter
55g/2oz plain flour
500ml/18fl oz milk
1 leek, cleaned, fine sliced and softened in 30g/1oz butter
salt and freshly ground black pepper

Method
1. Preheat oven temperature to 200C/400F/Gas 6.
2. Line a Swiss roll tin.
3. Make roulade: heat the oil, add onion and garlic, soften. Then add carrots and courgettes, soften for a further 1-2 minutes only. Put into a bowl with salt and pepper, sesame seeds, cheddar cheese and egg yolks.
4. Whisk egg whites until stiff and carefully fold into yolk mixture. Pour into a baking case and bake at the top of the oven for 15-20 minutes.
5. Meanwhile make the sauce. Melt butter, add flour, cook for 1-2 minutes and remove from heat. Add milk slowly, when all incorporated return to heat and cook until thick and bubbling. Remove from heat, add softened leek and seasoning, cover the whole with cling film next to the surface (this stops a skin forming and keeps the sauce warm).
6. On a cooling rack, place a clean tea towel. Take the roulade out of the oven (it should be springy to touch not rubbery). Carefully invert onto a tea towel. Spread filling evenly and roll up using the tea towel to help.
7. Slice vertically and serve immediately.