Spray mini donut maker with non-stick spray. In a medium bowl, mix the cake flour, baking powder, salt, sugar, and cereal until combined. Add in milk, eggs, butter, and vanilla extract. Whisk until well combined. Add batter to a large zipper bag and snip one corner to pipe batter into the donut maker. Bake for 3-5 minutes in the donut maker, repeat until all 5 batches are done.