Blueberries and water on the stove over medium heat in a medium saucepan. Add sugar if desired
Stir the blueberries and water often, smashing up some blueberries to produce juice, but not all of them
Mix together cornstarch and water in a mug or small bowl
Turn up the heat on the blueberries and start to bring to a boil, while stirring, pour in the cornstarch and water mixture. The blueberries will start to thicken up. Reduce heat to low and stir for 1-2 minutes. Remove from heat
Place prepared crusts on a baking sheet
Pour blueberries into the prepared crusts
Mix brown sugar and flour together in a small bowl. Mix in butter until fully incorporated
Sprinkle over pies
Bake for 15 minutes or until topping starts to brown and get bubbly
Remove from oven and let cool for 15-20 minutes or longer
Serve with a scoop of ice cream or whipping cream
Refrigerate any leftovers
Note
The nutrition facts do not include the mini pie crusts