Pour the water into a mixing bowl, then add the pancake mix. Whisk until the batter is smooth and well blended, making sure to scrape down the sides of the bowl.
For the Cinnamon Sugar Swirl
In a medium bowl, stir together the melted butter, brown sugar, and cinnamon until combined. Transfer the mixture to a piping bag or a zip-top bag. Let it rest for 10-15 minutes, allowing it to thicken slightly.
For the Icing
In a small bowl, whisk the powdered sugar and milk until smooth. Transfer the icing to a squeeze bottle or keep it in the bowl until ready to use.
Preheat a griddle or large nonstick skillet to 375 F (or medium-high heat). Lightly grease the surface. Scoop the pancake batter onto the hot griddle (about 3 tablespoons or a small scoop per pancake). Snip the tip of the cinnamon filling bag and pipe a spiral onto the top of each pancake. Cook for about 1 to 1 1/2 minutes or until bubbles begin to appear on the surface. Flip carefully and cook for another 1-2 minutes until the underside is golden.
Place two pancakes, cinnamon swirl facing up, on a plate and slightly overlap them. Drizzle each with icing - about 2 tablespoons per pancake - or as much as you like.