In a medium bowl, whisk together flour and cake mix. Stir in milk, eggs, oil, and vanilla and mix to combine. Lightly stir in sprinkles.
Preheat an electric griddle to 300 degrees. When heated, spray lightly with cooking spray and ladle about ⅓ cup batter onto the griddle. Carefully turn when edges are light golden brown. Continue cooking on the other side until the center springs back when lightly dented with finger.
Serve warm, drizzled with powdered sugar icing and lots of colorful sprinkles!
For Icing: In a small mixing bowl, combine powdered sugar, milk and vanilla extract and whisk until smooth and lumps are gone. You may need to adjust the consistency with more sugar or more milk, depending on desired thickness.
Drizzle onto warm pancakes and top with more sprinkles, if desired.