1. Heat your oven to 200°C/Gas Mark 6.
2. To make the pastry, mix the flour and salt together in a bowls. Gradually add enough water to form a dough.
3. Roll the dough out into a rectangle on a lightly floured work surface, approximately 20 x 30cm. Scatter half of the grated frozen butter and large over the pastry. Fold down the top third and fold up the bottom third as if folding a letter.
4. Turn the folded dough through 90 degrees and roll it out into a rectangle again. Repeat the process of adding the remaining frozen butter and lard and fold as before. Roll out and repeat 2 more turns with the dough to create the layers in the pastry.
5. Wrap the dough in cling film and leave to rest in the fridge for 30 minutes before using.
6. Take the chilled pastry from the fridge and roll out onto a lightly floured surface. Roll into a rectangle approximately 25cm x 35cm.
7. Take the spinach and place on the base of half the pastry, leaving a 1.5cm gap from the edge. Next add a layer of chopped peppers, cover with the grated cheese and top with a layer of Iberico ham. Brush the edges of the pastry with beaten egg.
8. Fold the pastry in half to cover the filling. Press the edges to seal. Brush the top with beaten egg and score a pattern on the top with a knife. Place on a baking tray and bake for 30 -35 minutes until the pastry is crisp and a rich golden brown colour.
9. Eat warm or cold with a salad.