Preheat oven to 400 degrees F. Line 14 muffin cups.
In a skillet add add apple ingredients except flour and cook over medium heat until apples are tender, about 10 minutes. Stir in flour to coat apples.
In a medium bowl whisk together flour, baking powder, baking soda, cinnamon and salt.
In a large bowl beat together applesauce, oil, and sugars till smooth. Beat in eggs, one at a time. Add vanilla and mix thoroughly.
Stir the flour into the butter mixture alternately with the buttermilk, beginning and ending with the flour and making sure everything is thoroughly combined. Gently stir in apples until just combined.
Spoon batter into cups, filling the cups, and smooth tops. Divide batter equally among prepared muffin cups. Bake until muffin tops are a pale golden and springy to the touch, 15 to 17 minutes. Cool muffins in pan for 5 minutes, then transfer to wire rack and cool 10 minutes before glazing.
To make the glaze, In a medium bowl mix together the melted butter, confectioners sugar, vanilla and water. Whisk until smooth. When muffins have cooled slightly, dip the muffin top into the glaze and allow the glaze to harden. Once hardened, dip a second time and allow to harden again.