First, start by preheating the oven to 375F. Line a baking sheet with parchment paper and set aside.
In a large bowl, combine the blueberries, lemon zest, lemon juice, corn starch and the 1/4 cup granulated sugar.
Roll out the store bought pie crust on the parchment lined baking sheet and mount the blueberries in the center or the pie crust leaving about 1-1.5 inches of border.
Fold the edges up on the blueberries, overlapping them as you go. Work gently to make sure that there are no cracks in the crust.
Brush the crust with heavy cream or milk and then sprinkle it with some sugar.
Bake in the preheated oven for 40-45 minutes or until the crust is golden brown and the fruit bubbly.
Serve this rustic blueberry galette with a scoop of vanilla bean ice cream or a dollop of whipped cream .