Carefully open each puff pastry sheet. Cut each sheet of pastry at creases, forming 3 strips. Cut each strip widthwise into 7 pieces.
Combine egg and milk; lightly brush egg mixture over pastry. Sprinkle with sugar. Place on lightly greased baking sheets. Bake at 400° for 10-12 minutes or until golden brown. Remove to wire racks to cool. Split into top and bottom halves.
In a saucepan, combine the flour and milk until smooth. Bring to a boil over medium heat; cook and stir for 1 minute or until thickened. Cool.
Transfer to a bowl; beat in the butter, sugar, vanilla, almond extract and salt until light and fluffy, about 10 minutes. Spread 1 tablespoonful on bottom half of each pastry; replace tops. Store in refrigerator.