Preheat your oven to 375°F (190°C).
Roll out the pie crust and fit it into a 9-inch pie pan. Trim any excess hanging over the edges and set aside.
In a medium saucepan over medium heat, combine the cranberries, granulated sugar, cornstarch, and salt. Stir well and cook until the cranberries start to release their juices, about 5-7 minutes.
Add the vanilla extract, lemon juice, and ground cinnamon to the mixture. Stir to combine and cook for another 2-3 minutes until slightly thickened. Remove from heat.
Pour the cranberry mixture into the prepared pie crust. Dot the top with small pieces of butter.
If desired, roll out a second pie crust and place it on top, sealing the edges. Cut a few slits in the top crust to allow steam to escape.
Place the pie on a baking sheet to catch any drips and bake in the preheated oven for 40-45 minutes, or until the crust is golden brown and the filling is bubbly.
Allow the pie to cool for at least 30 minutes before slicing and serving. This will help the filling to set up properly.
Optional: serve with whipped cream on the side.