Preheat the oven to 400 degrees F. Beat egg and water in a small bowl with a fork. Mix sugar and cinnamon in another small bowl.
Unfold the pastry sheet on a lightly floured surface. Brush the pastry with the egg mixture. Sprinkle with the sugar cinnamon mixture to within ½ inch of the edge. Starting at a long side, roll up like a jelly roll. Press the seam to seal. Cut pastry roll into 20 (½ inch) slices. Place the slices, cut-side down, onto 2 baking sheets.
Bake for 15 minutes or until the pastries are golden brown. Gently flatten the hot pastries with a spatula. Let cool completely on baking sheets on wire racks.
In a medium bowl, use electric mixer to combine cream cheese, lemon juice and powdered sugar. Mix until smooth. Add whipping cream to thin out the mixture. Mix until creamy and well combined. Add additional whipping cream, if needed, to create a spreadable consistency.
To assemble dessert bites spread a tablespoon of the sweetened cream cheese mixture onto each of the baked puff pastry rounds. Top with fresh blueberries. Garnish with mint, if desired. Serve immediately.