Preheat your oven to 425°F and line your baking sheet with parchment paper. Meanwhile, prepare Pastry Cream at least 4 hours before making the pastries.

On a floured surface, unfold and stretch out one puff pastry sheet into a 12x10-inch rectangle. Cut each sheet crosswise into sixteen 10x3/4-inch strips.

Each strip of dough should be wrapped around a cannoli tube or cream horn shape that has been greased. Place in rows on the prepared pan, 1 inch apart.

Beat together the egg whites and water in a bowl. Use it to brush over pastries and sprinkle with sugar.

Bake for 12 to 15 minutes or wait until golden brown. While the pastry is still warm, remove it from the pastry horn molder by slightly twisting it.

Let it cool on a wire rack. Repeat with the remaining puff pastry sheet.

Sugar, flour, and salt are stirred together in a medium-heavy saucepan. Stir in the half-and-half gradually. Stirring and cooking at medium heat until bubbling and thickened.

Cook and stir for an additional minute. Stir half of the heated mixture gently into the beaten egg yolks. Bring back the entire egg yolk mixture to the saucepan. Heat should be reduced after a gentle boil.

Cook and stir for 2 minutes. Remove from heat and stir in vanilla. Transfer to a bowl. Cover the surface with plastic wrap.

Place the pastry cream bowl in a ice bucket, and chill for five minutes while stirring. Wrap cling film over the surface. Let it cool for about 4 hours or until it is cold without stirring.

Meanwhile, beat the cream until soft peaks form in a small, cold mixing bowl. Gently incorporate whipped cream into pastry cream as it cools; make sure it's fully chilled before using. Makes 2⅓ cups.