Step 1In a large bowl, combine the meat with the salt and pepper. Mix to season, then divide the meat into 6 even portions. Shape the portions into patties, and set them aside to rest at room temperature for about 30 minutes before grilling.
Step 2Meanwhile, heat 3 tablespoons oil in a skillet over medium-high heat. Add the onions and cook, stirring frequently until softened, 3 to 4 minutes. Reduce the heat to medium, cover and continue to cook until the onions turn golden-brown, 15 to 20 minutes, stirring every 2 to 3 minutes. Reduce the heat to low and stir in the remaining tablespoon oil, chopped rosemary and garlic. Cook, stirring until fragrant, then remove from heat and set aside.
Step 3While the onion is cooking, in a small saucepan combine the dates and figs. Add the water and bring to a simmer. Cook 10 to 15 minutes until the mixture is thickened and reduced, then break up the dates and figs using the back of a spoon. Continue cooking, adding additional water if needed, until the mixture is reduced to the consistency of jam. Stir in the balsamic cream. Stir the fig and date mixture in with the onions. Taste, and season as desired with salt and pepper. Return the pan to low heat and cook, stirring until well combined. Remove from heat and set aside in a warm place. This makes about 1 1/2 cups jam.
Step 4About 15 minutes before assembling the burgers, place the cheese in the freezer to firm it up for slicing.
Step 5Heat a grill or skillet over medium-high heat. Warm or toast the buns as desired. Lightly oil the grill and cook the burgers 2 to 3 minutes on each side for medium, or as desired, careful not to overcook.
Step 6Remove the cheese from the freezer and slice into 6 thick (1-ounce) slices. To assemble the burgers, place a hot burger patty on the bottom of each bun and top with a slice of cheese. Add a dollop of the fig, date and onion jam to the top of each cheese slice and top with watercress. Top with the remaining bun half and serve immediately.