Mix the pancake batter according to the instructions on the package, but substitute soda water for the water to make the pancakes fluffier.
Preheat your griddle to low heat.
In a Ziploc bag, combine ½ stick of butter, sugar, and cinnamon. Use your hands to mix and soften the butter so the cinnamon and sugar blend evenly. Once mixed, snip the tip off one corner of the Ziploc bag to create a piping bag.
Melt 1-2 tbsp of butter on the preheated griddle. Pour pancake batter onto the griddle to form pancakes.
Immediately pipe swirls of the cinnamon butter mixture onto the tops of the pancakes using the Ziploc bag.
Squirt a little water around the pancakes on the griddle and cover with a dome or lid. Let the pancakes cook for 2-3 minutes. The pancakes should be fluffy on top and golden brown on the bottom. Do not flip the pancakes; they will cook through on their own.
In a small bowl, whisk together powdered sugar and milk until smooth. Drizzle the icing over the cooked pancakes.