If you're using homemade pie crust, you'll want to make that ahead of time. My suggestion is to make it first thing in the morning as it needs to chill for 2 hours before you roll it out.
Roll out the dough, either homemade or store-bought. If you're using homemade, roll it out to about 1/8 of an inch thick, just like you would for a pie. My homemade recipe yields two pie crusts. Even though it's not necessary to split the dough into two separate dough balls, I still do anyway. I find it helpful to work with one at a time, keeping the other one in the fridge until it's ready to come out.
Using a 4.5-inch biscuit cutter, cut out as many circles as you can from the rolled out dough. Once you've done this, gather up the remains, loosely wrap them in plastic wrap and set in the fridge while you work with the other dough ball.Roll out the other dough ball and cut out as many circles as you can. Combine the dough scraps together and form another dough ball. You'll find that the dough is not as pliable as it initially was. I will dip my fingers in some water as I'm working to reform the dough ball. This helps the dough come together better. It doesn't have to be perfect though. Once the circles are cut out, it's time to fill them. Put 1 tablespoon of blueberry filling in the middle of each circle. Be careful not to put too much filling or it will come out the sides of the hand pie while they bake.
Using your finger, lightly brush the edges of the circles with water before sealing them, helping to ensure they will stay closed. Fold the circles in half. I like to use a fork to hold the filling back as I close the circles. Once closed, crimp the edges closed with a fork. Be sure to wipe the blueberry sauce off the fork before crimping, or just use a clean fork. Using a sharp knife, cut three slits on the top of the pies, which helps to vent steam as they bake, preventing the filling from spilling out. A little bit of spillage is ok, we just don't want all of the filling coming out.
Whisk one egg and 1 tablespoon of milk together, and brush on the tops of the hand pies. Sprinkle with coarse sugar if desired. Place on a baking sheet lined with parchment paper. Refrigerate for 30 minutes, then bake for 30 minutes in an oven preheated to 350 F. Place the baking sheet on a rack just above the middle rack in your oven. When they're done, the tops should be golden brown and you will see the filling bubbling through the slits on top of the pies.
The filling will be VERY hot once you remove it from the oven. Since we are drizzling a glaze over the top of them, we'll need to let them cool down completely before adding the glaze.
To make the glaze, we'll mix together one cup of powdered sugar, one teaspoon of lavender extract, one tablespoon of blueberry sauce, and two tablespoons of milk. It will seem like it's not coming together, but keep mixing and you'll see that it does.
Once the hand pies have completely cooled off, use a spoon to drizzle the glaze all over the hand pies. It doesn't have to be perfect. In fact, I think they look better when they don't look perfect.Enjoy alone or with ice cream. If you want to warm them up a bit, pop them in the microwave for a few seconds.