Thaw the puff pastry.
Trim the spinach, rinse and spin dry. Bring a large pot of salted water to a boil, add the spinach and blanch until just wilted. Drain and then squeeze out the excess moisture.
Peel the onion and garlic and finely dice. Toast the pine nuts in olive oil over medium heat until light golden brown. Add the onion and garlic and cook briefly. Add the drained spinach and season with pepper and nutmeg.
Mix the ricotta with 3 eggs. Separate the remaining egg. Stir the egg whites into the ricotta then mix in the quark and season with pepper. Slice the olives and fold in.
Grease a pie dish and line with puff pastry.
Spread 1/3 of the cheese mixture over the base then top with 1/3 of the spinach. Repeat the layers with the remaining cheese and spinach mixtures. Top with a puff pastry lid, pressing the edges to seal. Cut a steam vent in the center.
Cut out small decorations from the remaining puff pastry and use to decorate the pie. Whisk the remaining egg yolk with a little water then brush over the pie and bake in a preheated oven (200°C) (approximately 400°F) for about 50 minutes. Serve warm or cold.