In a large bowl, whisk together the flour, cake mix, sugar, baking powder, and salt. In a medium bowl, whisk together the milk, oil, eggs, and vanilla.
Pour the wet ingredients into the dry ingredients, and mix until just combined (a few small lumps are okay). Let the batter sit for 10 minutes.
While the batter is resting, preheat a griddle or large skillet over medium heat. When the griddle is heated, stir in the sprinkles. Lightly grease the griddle, and pour the batter by 1/4 cup scoops onto the hot griddle.
Cook 3-4 minutes, or until there are bubbles all over the tops of the pancakes, then flip and cook and additional 2-3 minutes, until browned on the bottom.
Serve warm with whipped cream and sprinkles.