Heat the oil in a frying pan and gently fry the onion until softened. Leave to cool.
Lift the bread pan out of the machine and fit the blade. Put the dough ingredients in the pan, following the order specified in the manual. Add the onion and cheese with the water. Fit the pan into the machine and close the lid. Set to the dough programme.
Put the spinach in a saucepan with 1 tablespoon water and cover with a lid. Heat gently until the spinach has wilted. Drain and pat the spinach dry between layers of kitchen paper. In a bowl, mix together the Manchego with the nutmeg, garlic, raisins, pine nuts and seasoning.
At the end of the programme turn the dough out on to a floured surface and roll it out to a rectangle, about 40 x 30 cm (15 x 12 inches). Spread the filling almost to the edges. Roll up the dough, starting from a long side. Transfer the roll to a large, greased baking sheet with the join underneath. Bend the ends round to make a ring and push the ends firmly together to seal. Cover loosely with oiled clingfilm and leave in a warm place for about 45 minutes until risen by at least half again.
Brush the dough with beaten egg to glaze and sprinkle with extra grated Parmesan. Make vertical scores to the middle of the dough so that the filling is revealed. Bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 30–35 minutes until risen and golden. Serve warm or cold.