Spinach and summer herb roulade

Method

1. Preheat the oven to 200°C/fan180°C/gas 6. Line a 20cm x 30cm swiss roll tin with baking paper. 
2. In a heavy-based saucepan, melt the butter over a low heat. Stir in the flour with a wooden spoon, then cook for 3 minutes or until pale gold. Gradually add the milk, stirring constantly, until the sauce is smooth. Simmer briskly for 15 minutes, stirring regularly, until thick and velvety. Pour the sauce into a blender and leave to cool. 
3. Meanwhile, wilt the spinach in a large pan of boiling water for a few seconds, or put it in a colander and pour over boiling water. Drain and refresh under cold water. Squeeze out the water, then finely chop. Add the spinach to the white sauce, then blend, taste and season. 
4. Add the egg yolks to the blender, one at a time, whizzing to combine. Transfer the mixture to a large bowl, then set aside.
5. In a clean dry bowl, whisk the egg whites to soft peaks. Use a metal spoon to fold the whites gently into the spinach mixture. Quickly pour into the prepared swiss roll tin, then bake for 15-20 minutes until the mixture has risen and springs back slightly when pressed. Leave the roulade to cool in the tin. 
6. Put the cheese in a bowl. Beat in the herbs and zest, then season. 
7. Loosen the edge of the roulade with a knife and invert onto a large sheet of baking paper. Gently peel away the used baking paper from the roulade, then spread with the herb cheese, leaving a 2cm border. Working from the short side, use the baking paper sheet underneath to roll the roulade, gently but tightly, into a roll. Put the roulade on a board or serving plate seam-side down, then chill for 2-3 hours. Remove from the fridge 20 minutes before serving and trim the ends a little to tidy up the roulade.