Preheat oven to 375°F.
In a mixing bowl, combine flour, cocoa powder, baking powder, baking soda and salt.
In another mixing bowl, cream butter and sugar until light and fluffy. Add the egg (or replacer) and beat until combined.
Add the dry ingredients and applesauce alternately to the butter mixture starting and ending with flour. Mix just until combined, do not over mix.
Drop the dough by heaping tablespoons, 2" apart on a baking sheet. Bake for 10-14 minutes or until a toothpick inserted into the center of the cookie comes out clean.
Remove the pan from the oven and immediately using a thin spatula remove the cookies onto a wire rack. Cool completely.
In the meantime, make the frosting by creaming softened butter, powdered/ confectioner's sugar and vanilla extract until light and fluffy.
Once the cookies are completely cooled, spread some frosting on the cookie and sandwich with another cookie. Press lightly and then roll in the nonpareil. Set aside for 15 minutes to dry. Enjoy!!