The same kind you'd find cooling on a cartoon windowsill.
Turn the oven up to 375 F.
Mix the sugar, cornstarch, salt, and cinnamon together, and sprinkle that mixture over your blueberries.
Line a pie dish with the first layer of crust. Pour the prepped berries in, and dot them with butter. Cut the remaining crust into 1/2 - 3/4 inch wide strips, and lay them on top of the blueberries to make a nice lattice pattern. Crimp and flute the edges.
Bake the pie on the bottom shelf of the preheated oven for about 50 minutes. When the crust is golden brown, you're done.