Remove the dough from the refrigerator and allow to sit at room temperature for 10 minutes so that it is easier to roll out.
Preheat the oven to 425°F (roughly 220°C) and line 2 baking sheets with parchment paper.
Roll out the dough onto a heavily floured surface until the dough is about 1/8 inch thick. While you are rolling, make sure to move the dough around a bit, adding flour underneath the dough where necessary so that the dough doesn't stick to your work surface.
Using a circle cutter 6" in diameter (a bowl, plate or even cake pan), cut as many circles out of the dough as possible and place onto the baking sheets lined with parchment paper.
Shape the scraps of dough back into a ball, re-roll the dough to 1/8 inch thick and cut out more 6" circles. Repeat this process until you have 8 circles cut out. Do your best to handle the dough very minimally.
Place all 8 circles of dough onto the two baking sheets.
Spoon the blueberry ginger filling onto each dough circle, leaving the outer 1 inch of dough without filling. When scooping the filling, be sure to strain any liquid before placing it onto the dough to avoid a soggy pastry bottom.
Fold the edges of the dough over itself until the filling is incased.
Whisk 1 large egg with 1 Tbsp of heavy cream and brush the folded over edges of pastry with the egg wash.
In a small bowl stir together 5 Tbsp of coarse sugar and 2 tsp of freshly grated ginger. Sprinkle this mixture onto the egg washed pastry.
Bake for 20-25 minutes or until the pastry is golden brown. Remove from the oven to cool.
As soon as the blueberry ginger galettes come out of the oven, use a fork to mix up the filling slightly. This will break up the whole blueberries and encourage a gooey center.
Optional: drizzle some hot honey over the hot galettes.
Serve with a scoop of vanilla ice cream and enjoy!