Beat the egg with the milk. In the food processor combine the flour, yeast, salt and cold butter into coarse crumbs. Add the milk-egg mixture slowly, since you might not need all the milk, or perhaps you will need a little more. Also fold in half the pistachio nuts. Do not beat for too long, the dough must be well blended, but not too smooth. Cover with plastic wrap and place in the refrigerator for at least 4 hours or overnight. Allow the dough to reach room temperature and thoroughly knead for a few minutes. Divide into six equal balls. Grease the baking moulds and place the balls in them. Fry the spinach in a wok, squeeze out the moisture, distribute over the buns. Crumble the goat’s cheese over with the remaining pistachios. Allow to rise again for 90 mins. Preheat the oven to 180°C (350°F/Gas 4) and bake until golden brown, (approx. 30 minutes).