Line a plate with buttered parchment paper. In a saucepan, dry the chopped spinach, then add, off the heat, the cream, egg yolks, parmesan, salt, and pepper. Beat the egg whites until stiff peaks form and gently fold them into the mixture. Spread on the paper and bake for 10 to 15 minutes in the oven (350°F). Flip the cooked dough onto another sheet and roll it up without squeezing too hard. Meanwhile, mix the filling ingredients. Spread the filling over the dough and roll it up without the paper. Cut into 1cm slices and serve chilled.