Preheat the oven to 450 degrees. Whip the egg whites until well blended. Add the flour and the sugar until blended, and then add the butter and cream. Mix well.
Spread the batter on a lightly greased cookie sheet with the back of a spoon trying to achieve a thin, even circle of batter. Bake for just a minute or so (watch carefully so they don’t burn). Cut in half with sharp knife and roll from one end to the other to make a cone shape. Better yet, use horn molds like you’d use for making cream horns and shape the tuiles as soon as they come from the oven, but careful not to burn your hands. You could also shape them over an upturned custard cup for a ruffled cup shape that is appealing as well.
You can add a tablespoon of cocoa to the batter for chocolate cones or any flavoring you like. You could even sprinkle very tiny chopped nuts into the batter as it’s spread on the baking dish to give them more texture. Let dry and serve with your favorite sorbet or ice cream.