Preheat the oven to 350 degrees F. Line a baking sheet with parchment paper.
For the streusel topping: In a medium bowl, stir together the flour, brown sugar, granulated sugar, ginger, salt and lemon zest. Using a pastry cutter or two knives, cut in the butter until the mixture is moistened and clumpy.
Spread the streusel into an even layer on the prepared baking sheet, squeezing it a bit to form large clumps. Bake for 15 minutes, until the clumps are slightly dry and lightly toasted on the outside. Remove from oven and cool completely on the baking sheet. (See Cook's Note)
For the cake: Bake the cake in two 9-inch cake pans according to package instructions. Cool the layers completely.
For the frosting: Combine the cream cheese, butter, confectioners' sugar and vanilla in a bowl and beat with an electric mixer until light, fluffy and well combined.
Assemble the cake: Place one cake layer on a cake stand or plate. Top with half of the frosting, then dollop the pie filling around the center and sprinkle blueberries around the edge. Place the second cake layer on top, cover with the remaining frosting and sprinkle with more blueberries. Top with a generous sprinkling of the streusel. Dust with powdered sugar and serve.
The streusel can be baked ahead of time and stored in an airtight container for up to 2 days, or stored uncooked in the freezer for up to 2 months. Just increase the baking time by a couple of minutes if baking it off from frozen.