Add the dry ingredients to the blueberries, including the lemon juice and a little bit of lemon zest, and stir.
Unroll the crust and cut 4-inch dough circles out with a circle cutter. Gather the scraps, re-rolls, and cut out additional circles. You will need 12 total.
Press the pie dough into the greased muffin cups. Add the filling to the pie shells so they are evenly divided.
Use the strips to make a lattice pattern. Press the edges down against the bottom of the crust to seal. Trim the excess dough or press the top edge of the crust to close each pie.
In a small bowl, whisk together the water and egg. Brush the tops of the tiny pies, then sprinkle coarse sugar.
Bake for 20-25 minutes. If the top of the pies gets too dark while baking, cover them with aluminum foil. Remove once the blueberry mixture is bubbling through the top of each pie.