Preheat oven to 200 degrees.
In a large shallow bowl, whisk together milk, eggs, sugar, cinnamon, salt, and vanilla until well blended. Slowly whisk in flour and baking powder until smooth.
Add cornflakes to a second shallow bowl and place next to the batter. Heat 1 inch oil in a heavy skillet to 325 degrees.
Working with 1 or 2 bread slices at a time, dip bread in batter and allow any excess to drip off and back in to the bowl.
Roll generously in cornflake crumbs. Immediately fry in oil until golden brown, about 1 minute per side.
Drain on paper towels and transfer to a baking sheet in oven to keep warm. Repeat with remaining bread slices.
Serve warm with your favorite toppings such as maple syrup, powdered sugar, whipped cream, fresh fruit, or candied pecans.