Preheat broiler to high.
Crush 4 cloves of garlic and place in a microwave-safe dish or small saucepan with the butter and oil. Heat in microwave for 1 minute or, if cooking on the stovetop, place over moderate-low heat for 3 minutes.
Split each loaf of bread in half lengthwise and scoop out the insides to make room for the Caesar chicken filling. Toast bread under broiler until it is golden brown in color.
Brush bread liberally with garlic oil, sprinkle with 1/4 cup cheese and return to broiler to brown, about 30 seconds.
Place the shredded chicken into a medium-size bowl. In a blender, combine EVOO, lemon juice, Worcestershire sauce, anchovy paste, mustard, 1/2 cup grated cheese, salt and lots of freshly ground black pepper. Pulse the blender to combine the dressing and pour it over the chicken. Toss the chicken lightly to coat.
Cut the core end off from the heads of romaine and remove the thick vein from the center of the leaves. Line each bottom half of the cheesy, toasted garlic bread with the lettuce. Place the chicken on top of the lettuce and sprinkle with the remaining grated cheese. Top with the other bread half and secure the sandwich with two skewers. Slice the loaf into individual sandwiches and serve.