1. Mix the salt, sugar, water, bay leaves, allspice and thyme in a pan and heat until the salt and sugar dissolve. Let cool. Trim the fat off the loin. (It's okay to leave some fat on top for flavor.) Put the loin in a pan just large enough to hold it, with the liquid, and pour the brine over the pork. Large industrial-sized zip lock bags work well also. They can be thrown away after marination is done. Let the pork marinate overnight or at least 6 hours in the refrigerator.
2. When the pork is fully brined, remove it and wipe it dry. Heat the oven to 350 degrees. Heat a saute pan over high heat and sear the loin and brown on all sides, about 5 minutes. Put the loin in a roasting pan and roast the whole pork loin for 45 minutes to an hour, checking for doneness. It should reach an internal temperature of 160 degrees. You may need extra time in the oven. Let the loin cool and cut it into thin pieces of your liking to fit on your toasted bread.
3. Heat 3 tablespoons of the olive oil in a saute pan on medium heat. Put the garlic and shallots in the pan, turn the heat to low, and sweat them for 10 minutes. Do not let them brown. Stir in the prosciutto and half the rosemary, finely chopped. Set aside to cool. You will use this mixture as a garnish for the lamb.
4. To make the crostini, thinly slice the french loaf and brush the tops with olive oil. Sprinkle with salt and freshly ground pepper. Place in a single layer on a sheet pan and bake in the oven at 350 degrees for 7-10 minutes, until golden brown.
5. To assemble the appetizer, layer a piece of pork loin on each crostini and use a melon-baller or your hands to form a small ball of proscuitto topping. Place the prosciutto on top of the pork and finish with a single sliver of rosemary stuck into the topping.