Combine the flour, butter, and salt in a food processor (or by hand, if you don't have one), until it resembles oatmeal.Add ¼ cup iced water (and more if needed), and keep processing until a smooth dough forms.Make a ball with the dough, wrap in film or in a plastic bag, and refrigerate for ½ hour.In the meantime, remove excess water from the cooked chard and spinach, by squeezing them. Chop coarsley.Heat the oil in a pan over medium heat and saute the onion and garlic for 5 minutes, stirring. Turn the heat off, and add the greens, 3 eggs, cheese, salt, pepper, nutmeg, and the bread (squeezed and crumbled). Mix well.Preheat the oven to 350 F.Roll half the dough on a floured kitchen counter until thin (but not transparent).Line a 9-inch baking pan with half the rolled dough, and pour the chard filling, reserving 5 tablespoons of it.Make 5 dents on the surface of the filling, and break one egg on each. Cover each egg with 1 tablespoon of the reserved filling.Roll the remaining dough, and cut a circle 1-inch larger than the pan.Put the stretched dough over the tart, and seal the edges, pressing with your fingers.Beat the remaining egg in a small bowl with 1 tablespoon water, and brush all over the top of the tart.Bake for 45 minutes, or until golden.Let it stand for 20 minutes before cutting it.Serve with lime wedges on the side.