Put the cornflakes in a large bowl and pour half of the tempered chocolate over them.
Using a rubber spatula, quickly fold the cornflakes into the chocolate until they're evenly coated; add the remaining chocolate and fold gently until all of the cornflakes are generously coated with chocolate.
Working quickly and using a teaspoon, scoop the chocolate-covered cornflakes onto the prepared baking sheet and shape them into free-form clusters with a second teaspoon.