Preheat waffle iron to medium heat.

In a large mixing bowl combine Bisquick, oil, eggs and Zevia soda until combined.  The carbonation in the soda may fizz a bit but it will calm down!

Fold in rainbow sprinkles.

Using a 1 c measuring cup, scoop about 2 cups batter onto hot waffle iron.  Cook about 3 minutes.  (Each waffle iron is a little different so amount of batter used and cook times may vary)

Remove waffle from iron and place on cooling rack for about 10 minutes.  Repeat with remaining batter.

Make 1/2 batch buttercream icing following recipe card below.

Place 2nd waffle on top.  Cover top with whip cream.

Repeat with 3rd and 4th waffles.

Melt 1 cup buttercream icing in microwave on low power for 25 seconds.  Stir well.  Add 2 tbls milk and stir until well blended.  The milk will want to separate but keep stirring!!

Using a disposable pastry bag, fill bag with melted icing. Trim tip of icing bag about 1 cm from end.

Working from the outer edges of the top of the waffle cake, begin drizzling icing down sides.  After all sides have been drizzled, fill top with remaining icing.

Top cake with either a scoop of buttercream icing or a large clump of whip cream.

Decorate with sprinkles, candles, gumballs and colorful chocolates.