Preheat the oven to 425 degrees.

Combine the blueberries, sugar, flour, cinnamon, lemon zest, and salt in a medium mixing bowl. Mix until well combined and let sit at room temperature while you roll out your crust.

On a lightly floured work surface, roll out 1 of the crusts to 11 inches in diameter. Carefully transfer to a 9-inch pie plate. Spread filling over the crust, then refrigerate pie while you work on the top crust.

Roll the top crust out on a lightly floured work surface to 11 inches in diameter. Cut stars out of the top with a small star-shaped cookie cutter.

Remove pie from the refrigerator and carefully lay the top crust over the pie. (I like to drape the crust over my rolling pin to transfer it.) Pinch the edges to seal the crust and trim off the excess dough. Combine the heavy cream and egg yolk in a small bowl and brush over the top crust.

If desired, decorate the top of the pie with the cutout stars by brushing both sides of the stars, then pressing lightly onto the crust.

Place the pie on a large baking sheet and bake for 40 to 50 minutes, until the pie crust is golden brown. If pie gets too dark, cover with foil in the last few minutes of baking. Allow to cool at room temperature before slicing and serving.