To make the pastry, sift the flour,
baking powder and a pinch of salt together.
Make a well in the centre, add the
butter and egg yolk and gradually work the flour into the butter and egg
yolk and gradually work the flour into the butter and egg yolk with
fingertips.
Gather the dough together, then roll
it out gently to a rough round on a floured surface.
Lift the round into a 9 inch fluted
tart tin with a removable base and press the pastry into the corners and
up the sides.
Trim the top edge with a knife, then
chill in the refrigerator for 30 minutes.
Make the filling, melt the butter in a
small pan, add onion, cook gently for 5 minutes, stir, until softened
but not colored.
Add spinach, nutmeg, season to taste
with salt and pepper, stir well to mix, leave to cool.
Line the pastry case with greaseproof
paper and fill with baking beans.
Bake in oven 375F, gas mark 5, 15
minutes.
Lift out the paper and beans and set
the pastry case aside.
Reduce oven temperature to 325F, gas
mark 3.
Place the mascarpone into a large bowl
and whisk in the pecorino, egg and egg yolks.
Add the cooled spinach and salt and
pepper to taste, blend well together, spoon into the pastry case.
Bake in the oven for 30 minutes,
covering the edge of the pastry with foil if it shows signs of over
browning.