Preheat oven to 400 degrees. Cut the tip off the head of garlic. Season with salt and pepper, drizzle with olive oil and wrap in foil. Place in oven and roast for 40 minutes. After garlic has been roasting for 20 minutes, place tomatoes on a baking sheet, drizzle with olive oil, season with salt and pepper and place in the oven. Roast until the tomatoes burst, about 10-15 minutes. Remove from oven and place in a medium bowl. Remove garlic from oven, cool slightly to handle, unwrap and squeeze the garlic into the bowl with the tomatoes. Mash the garlic and tomato mixture. Toast the French bread halves in the oven until lightly browned. Remove from oven and spread the tomato mixture on the bread. Top with the shredded gruyere cheese, return to the oven until cheese melts, about 5 minutes. Sprinkle with chopped parsley.