Preheat the oven to 375℉. Line a rimmed baking sheet with parchment paper. Arrange 18 frozen tart shells (or homemade) on the prepared pan. Distribute the blueberries between all 18 tart shells. Place the pan of tart shells in the freezer while you prepare the filling.
In a medium-sized bowl whisk together the egg yolks, sugar, vanilla extract, cornstarch, and salt until smooth and slightly frothy. Whisk in the whipping cream until fully incorporated.
Take the tart shells back out of the freezer and distribute the custard mixture evenly between all the tart shells on top of the blueberries. Bake in the preheated oven for 20-25 minutes or until mostly set and the tart shells are slightly golden. Let cool to room temperature on a wire rack before transferring to the refrigerator to chill fully. Enjoy!
Notes
Storebought frozen unsweetened tart shells are what this recipe was tested with. You could make homemade tart shells instead, though! Or use gluten-free tart shells to make these tarts gluten-free.
Fresh or frozen blueberries would work for this recipe. I typically use cultivated blueberries to make them because they are larger and juicy but I think smaller wild blueberries would be great too.