Preheat your waffle iron according to the manufacturer's instructions. Choose a low setting if you plan to toast these waffles later, or choose a higher setting if serving immediately

In a large mixing bowl, whisk together the flour, sugar, baking powder, baking soda, and salt.

In a separate bowl, combine the buttermilk, eggs, vegetable oil, and vanilla extract. Whisk until well combined.

Add the wet ingredients to the dry ingredients. Use a rubber spatula to stir the mixture together until almost combined, but a few lumps of flour remain.

Gently fold in the rainbow sprinkles, and mix until no streaks of flour remain and the sprinkles are evenly distributed.

Spray the top and bottom of the hot waffle iron with cooking spray. Scoop a spoonful of batter onto the waffle maker. Depending on the size of your waffle iron this can range from 1/3 cup to 1/2 cup of the waffle batter. For my model, I use 1/2 cup of batter to make a 6" waffle.

Spread the batter slightly with a rubber spatula so that it's evenly distributed in the center of the waffle maker. Do not spread the batter all the way out to the edges.

Close the lid of the waffle maker and allow the waffle to cook until it is golden brown and crisp, following the manufacturer's directions.

Carefully remove the waffles from the waffle maker and transfer them to a wire rack. Store the waffles in a warm oven until ready to serve.

Repeat the above process until all the batter has been cooked off and serve immediately.