Place blueberries in a pot and heat over medium heat until berries start to break down and release juices, about 7-10 minutes.

In a separate bowl whisk together the sugar, salt, and cornstarch. Add to blueberries and mix well. Heat until the mixture starts to bubble and thicken, about 2-3 minutes.

Remove from heat and stir in lemon juice. Cool off in fridge or go ahead and bake it in a pie.

Place one crust in pie pan and trim edges. Pour the filling in. Dot the top with 1-2 tablespoons butter. Moisten the crust edge with milk to help the top crust stick. Place top crust on filling and trim to fit. Make sure to cut some vents in it to let the pie breathe. With a spoon or pastry brush, moisten the top of the pie with milk and then sprinkle with 1-2 teaspoons sugar.

Bake in 425 degree oven for 15 minutes and then reduce heat to 350 degrees and bake for 30 more minutes or until top is lightly browned and filling is bubbly.