Preheat oven to 350°F and line a baking sheet with parchment paper or silicone liner.
In a mixing bowl, beat together cream cheese, 2 tablespoons sugar, lemon zest, and almond extract until well-blended and smooth.
Toss the blueberries with the remaining 1 tablespoon sugar, smushing a few to release juices.
Whisk together the egg and water in a small bowl.
Roll out the puff pastry into an approximate square and cut into 9 squares. (See note.)
To shape as photographed, make a slit about ½-inch in starting at the top right corner and going down just short of the bottom right corner. Repeat, starting at the top right corner and going across, stopping short of the top left corner. You should now have a flap. Repeat on the opposite corner (bottom left) to create two flaps. Fold over each corner to rest on the inside square, dabbing on a little of the egg wash to help the layers adhere. Transfer to the baking sheet.
Spoon some of the cream cheese mixture into the center of the square, then top with blueberries.
Bake for 20-25 minutes, or until golden brown. Let cool and dust with powdered sugar, if desired.
Notes
How you shape the danish will determine if you need 1 or 2 sheets of puff pastry. If shaping as photographed, you will need 2 sheets. If making basic rectangles, you will only need 1.
This makes 18 small danishes or 9 larger danishes.