In a chilled mixing bowl, combine heavy cream and powdered sugar, then whisk until stiff peaks form, about 2-3 minutes. Refrigerate until ready to use.

In a large mixing bowl, whisk together the all-purpose flour, baking powder, salt, white sugar, and yellow cake mix until well combined.

Add the vanilla extract, egg, melted butter, and whole milk to the dry ingredients. Whisk gently until just mixed; lumps are okay.

Gently fold in the rainbow sprinkles, being careful not to overmix the batter.

Heat a non-stick skillet over medium heat and lightly grease with butter or non-stick spray. It's ready when a few drops of water sizzle.

Using a cookie scoop, pour the batter into the skillet to form pancakes about 3-4 inches wide. Cook for about 3 minutes until bubbles form on the surface.

Flip the pancakes carefully and cook for an additional minute until golden brown.

Serve the pancakes warm, topped with whipped cream and additional sprinkles.