Grease
a 23 x
33 cm/9 x 13 inch Swiss roll tin and line with nonstick baking
paper. Melt the butter in a saucepan, stir in the
flour and mustard, and cook over a low heat for 1
minute, then gradually add the milk, stirring until
evenly blended.
Bring the sauce slowly to the boil,
stirring constantly until it thickens. Cook over a
low heat for 2 minutes. Remove the pan from the
heat, leave to cool slightly, then beat in the
cheese, egg yolks, herbs, salt and pepper.
Whisk the
egg whites until stiff and fold into the sauce
until evenly incorporated. Pour the mixture into the
prepared tin and place in a preheated oven,
200°C (400°F), Gas
Mark 6, for
12-15 minutes until risen and firm to the touch.
Remove
from
the
oven and set
aside to cool. Reduce the temperature
to 190°C (375°F), Gas
Mark 5.
Meanwhile, prepare the filling. Beat the cheese and
half the oil together until smooth and season with salt and pepper.
Heat the remaining oil in a frying pan and fry the leek
for 5 minutes. Drain the spinach in a colander,
pressing with a wooden spoon to squeeze out the
excess moisture, and chop finely.
Add to the leeks, season
with nutmeg and cook gently for 5 minutes.
To assemble the roulade, turn it out of the tin and
carefully peel away the paper. Spread the softened
cheese and then the spinach mixture on the roulade.
Roll up from a short end and place on the
oiled Swiss roll tin. Brush with oil and bake for
20-25
minutes.
Serve
hot, in
slices, with
fresh tomato sauce.