01 -
Combine blueberries, sugar, and lemon juice in a small saucepan over medium heat. Stir water and cornstarch together in a small bowl, add it to the berries, and cook 4-6 minutes until glossy and thick. Cool completely.
02 -
Beat softened cream cheese, sugar, vanilla, lemon zest, and salt until smooth and spreadable. Keep chilled if the kitchen is warm.
03 -
Heat the oven to 400 F and line a baking sheet with parchment. Unfold each puff pastry sheet on a lightly floured surface and roll just enough to smooth the seams.
04 -
Transfer the pastry to the baking sheet. Leave the center third whole and cut 1-inch angled strips along both long sides. Spread cream cheese down the center and spoon cooled blueberry filling over it.
05 -
Fold the top and bottom ends over the filling. Alternate strips from each side across the center, overlapping slightly. Chill the braid for 10 minutes if the dough feels soft.
06 -
Whisk the egg with 1 tablespoon water and brush it over the pastry. Bake for 22-26 minutes, until puffed and deeply golden.
07 -
Whisk powdered sugar, 1 tablespoon milk or cream, lemon juice, and vanilla until smooth. Add more milk only if needed. Cool the braid for 15 minutes, drizzle with glaze, and slice.