Mix all topping ingredients together by rubbing with fingers, set aside. (I got a little lazy and melted the butter, as a shortcut from having to soften my rock hard butter!) In a large bowl, mix your flour, sugar, baking powder, baking soda, and salt. In another bowl, whisk together your eggs, applesauce, oil, and vanilla.Mix it well. Add applesauce mixture to flour mixture, stir till wet. With an ice cream scoop, fill each each muffin well about 2/3 full. (You an also bake as a cake, or as smaller muffins). Sprinkle topping over batter. Bake at 350°F for approximately 25 minutes.