01 - Combine crushed vanilla wafers with melted butter in a bowl. Press the mixture firmly into the bottom of a 9x13 inch dish. Refrigerate while preparing the filling layers.
02 - Combine blueberries, granulated sugar, lemon juice, and water in a medium saucepan. Cook over medium heat until the berries burst and begin to release their juices. Whisk cornstarch with a splash of water to form a slurry, then stir it into the berry mixture. Simmer until thickened, about 2 minutes. Remove from heat and let cool completely.
03 - Beat cream cheese and powdered sugar together in a large bowl until completely smooth. Incorporate lemon zest and juice, mixing until evenly blended. In a separate chilled bowl, whip the heavy cream to stiff peaks. Gently fold the whipped cream into the lemon mixture in two additions, being careful not to deflate the volume.
04 - Spread half of the lemon cream evenly over the chilled cookie crust. Spoon half of the cooled blueberry sauce on top and spread gently. Repeat with the remaining lemon cream, then finish with the remaining blueberry sauce.
05 - Cover the dish tightly with plastic wrap and refrigerate for at least 4 hours, or overnight for the cleanest slices and best flavor development.
06 - Spread whipped cream over the top layer just before serving. Garnish with fresh blueberries and a dusting of lemon zest. Cut into squares and serve chilled.