Preheat oven to 350 degrees F. Line a baking sheet with parchment paper and set aside.
In a medium mixing bowl, add oats, flour, baking powder, baking soda, ground ginger, cinnamon, nutmeg, cloves and salt. Whisk to combine.
Melt butter and pour into a small mixing bowl. Add egg, vanilla extract, maple syrup and molasses. Whisk to combine.
Pour wet ingredients into the bowl of dry ingredients. Stir until incorporated.
Use a ¼ cup cookie scoop to transfer the balls of cookie dough onto prepared baking sheet. Use the back of a measuring cup or bottom of a clean glass to flatten the cookie dough balls.
Bake for 12 minutes-15 minutes or until golden brown.
While cookies are baking, prepare the icing. In a small bowl, stir together confectioners sugar, vanilla extract, 1 tablespoon of milk and cinnamon. If icing is too thick, add ½ tablespoon of milk at a time until desired consistency is reached.
When cookies are finished baking, frost each cookie. Sprinkle cinnamon onto iced cookies, if desired.