Preheat griddle to 350 degrees F or or heat a skillet over medium heat.
Add cereal to a shallow pie dish or plate. Add all ingredients, except the bread and cornflakes to a blender or to a shallow dish and whisk well to combine. If whisking by hand, it's okay if the flour doesn't mix in completely smooth.
Add the batter and the cereal to two separate shallow dishes. Dip each piece of bread into the egg mixture on both sides and then press gently into the cereal, flipping to coat both sides.
Melt a small piece of butter in a skillet or griddle over medium heat (or grease with cooking spray). Place the bread slices on the hot skillet and cook for a few minutes until golden on the bottom and then flip and cook on the other side.