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!