Combine all cake round ingredients in a small bowl; mix well. Mixture will seem dry; but keep working to combine to form a dough. Cover and chill for 30 minutes to 1 hour.
Preheat oven to 400°. Working with a portion of the dough at a time, roll to a 1/2-inch thick snake-like rope. If dough is sticky, roll out on parchment sprinkled with a little powdered sugar. Cut ropes into 4", 5", 6", 7", 8", 9", 10", 11", 12", and 13" pieces. Join ends of each rope to form circles. Place on a parchment-lined baking sheet, placing small rings inside of larger but not touching and making sure they are fully round.
Bake at 400° for 10-12 minutes or until just golden. Allow to cool.
Meanwhile, combine icing ingredients in a medium bowl; whip well with a wire whisk. Transfer icing to a piping bag with tip or to a sandwich bag with a snipped corner.
Starting with the largest ring, make a zig-zag line of icing around the top of the ring. (i sprinkled edible glitter on icing for extra sparkle). Top with next largest ring and repeat all the way to the top. (if you are confused by the size of the rounds, practice making your stack before icing them together.)
*traditionally, this holiday/wedding cake is 18 rings tall and adorned with small, decorative flags or flowers. i loved the fresh greenery i had for the winter and couldn't resist topping my holiday kransekake with them.