Preheat the oven to 220°C/425°F/gas 7 and lay out a large sheet of thick tin foil (about 60cm long).Drizzle one half of the foil with olive oil and pile the gnocchi on top. Add the capers and tomatoes, squashing a couple of tomatoes to release their juices. Destone and tear over the olives, finely slice and scatter over the chilli (deseed if you like), then tear over the anchovy fillet and herbs.Drizzle everything with 1 tablespoon of oil and season with black pepper. Squeeze over the lemon juice, add a splash of water, then finely grate over the Parmesan.Crack and separate the egg. Brush around the perimeter of the foil with egg white (save the yolk for another recipe), then fold in the foil overhang, tightly rolling the sides in towards the centre to seal.Carefully transfer the bag to a baking tray, then place the tray on the hob over a medium heat for 5 minutes, or until the bag starts to puff up.Bake on the middle shelf of the oven for 15 minutes, then remove from the oven and leave to steam for 5 minutes. Dollop over the crème fraîche, to serve. Delicious served with a seasonal salad, or an extra portion of steamed or roasted seasonal veg on the side.