Wash the kale carefully under cold running water. Depending on the type, you may want to discard the heavier stems (it’s easy to just pull the leafy parts off, leaving the stem behind). Tear the leaves into large pieces and put the kale in a stock pot with enough cold water to cover and 1/4 tsp of the salt. Cook, tightly covered, over medium heat for about 15 minutes or until the kale is very tender. Drain the kale through a sieve, pushing on it with a spoon to squeeze as much water out of it as possible. Then chop very finely.

Meanwhile, in a heavy 2 quart saucepan, melt the butter over medium heat. Remove the pan from heat and stir in the flour. Add the milk and cream all at once. Return the pan to low heat and beat vigorously with a wire whisk until the sauce comes to a boil and is smooth and thick. Add the remaining salt, pepper and chopped kale. Cook for another few minutes, just until the kale is warmed through.