Preheat oven to 350 degrees. In a large bowl combine flour, oats, sugar, baking powder, salt, and cinnamon. In another bowl, beat the egg. Add milk, applesauce, and oil to egg and whisk until well combined. Add egg mixture to flour mixture and stir until just combined. Scoop into muffin tin and bake 20 to 22 minutes or until light brown and center is set. Remove from the oven and let cool.
For truffles:
In a large bowl, break up muffins with a fork. Stir in 1/3 cup frosting. You want the mixture to be a little dry so don't add all the frosting at once. Work with it and see if you need all of it. Add remaining frosting if needed. When everything is well combined, roll into small balls and place them on a sheet of waxed paper. I use a small ice cream scoop to get even balls. Place in the freezer for an hour to set.
Melt chocolate and vegetable shortening in a microwave at 30-second intervals. Stir until smooth. Stick a toothpick in the center of the ball where it is secure. Dip ball in chocolate then place it on a sheet of waxed paper or parchment paper. Top with sprinkles if desired. Allow chocolate to cool and harden for about 1 hour. Store in an airtight container in the refrigerator.