Put prawns and wine in a large sauté pan over a high heat and cook covered for about 5 minutes. Remove prawns with a slotted spoon. When they have cooled a little remove shells. Add olive oil, onions and garlic to the prawns cooking liquid. Cook, stirring over a medium heat until most of the liquid has evaporated. Add the tomatoes and parsley. Simmer, covered, for 10 minutes then uncovered for 20 - 30 minutes until you have a not too liquid sauce. Add a little salt, plenty of pepper and the shelled prawns. Mix well and put the mixture in 4 small dishes or ramekins. Sprinkle with the feta. Bake in a preheated 220° C gas 7 oven for about 15 minutes, until the cheese has melted and begun to brown on top.