Preheat oven to 400 degrees Fahrenheit. Line a baking sheet with parchment paper.
Unfold puff pastry and using a rolling pin, roll out into a 10 to 12 inch square, removing creases. Transfer to parchment lined baking sheet.
In a bowl, add blueberries, granulated sugar, lemon juice, cornstarch, vanilla extract, and cinnamon. Stir until cornstarch dissolves and ingredients are evenly incorporated. Gently pour blueberry filling into the center of prepared puff pastry, leaving a 2-3 inch border around the edges.
In a clockwise pattern, fold edges of dough over filling (pinching together as needed), leaving a small circle of filling visible in the center.
Optionally, brush edges of crust with heavy cream and sprinkle with additional granulated sugar.
Bake for 30 to 40 minutes, or until crust is golden brown and filling is bubbling. Remove from oven and allow to cool before slicing and serving.
Store any leftovers in a sealed container at room temperature for 2-3 days.
Optionally, top galette with a scoop of vanilla ice cream or whipped cream before serving.
Puff pastry can be substituted with a traditional pie crust if desired.
If using frozen berries, strain off any extra juices before mixing your filling.