Beat egg yolks and sugar together.
Mix the cornstarch with the water and cook until thick and clear. Remove from heat. Stir into the egg mixture. Return to heat and cook, stirring, until thickened.
Add the salt and the lemon juice.
Whip the cream. Fold into the mixture with the cinnamon just before serving.
Delicious on fruit salad but also on such diverse dishes as puddings and pancakes.