Preheat oven to 300.
Add the blackberries, saison, powdered sugar, cornstarch and salt to a pot over medium high heat. Bring to a low boil, stirring frequently until thickened, about ten minutes. Set aside.
Roll out puff pastry on a lightly floured surface. Line a 9-inch spring form pan, letting the less hang over the sides. .
Beat the cream cheese in a stand mixer until light and fluffy. Add the sugar, egg and vanilla, beating until well combined. Add the flour, cornstarch, salt and beer, stir on low speed until well combined.
Add to the spring form pan in an even layer.
Pour the blackberry sauce evenly over the cheesecake layer. Fold the excess puff pastry over the top of the tart.
Bake at 300 for 1 hour or until the puff pastry is golden brown. Allow to cool to room temperature, then refrigerate until chilled, at least 3 hours and up to over night.