Mix all ingredients together except avocado, cheese and 1/2 cup salsa. Separate meat mixture into eight equal amounts and make thin hamburger patties with each. Place one patty on a cookie sheet, lay three to four avocado slices in the center, and top with a mound of cheese. Place another patty on top and mend the sides together. Repeat with the rest of patties. Bake at 375 degrees for 20 minutes. Remove meatloaves from oven, spoon one tablespoon of salsa on top, and sprinkle with cheese. Place back in oven for 15 minutes. Let meatloaves set for about 5 minutes before serving.