Preheat oven to 325 degrees F. In a medium saucepan, combine sugar, cornstarch, and salt. Whisk in the half-and-half and cook over medium heat until mixture is thickened and bubbly, stirring occasionally.
Remove from heat, add butter, brown sugar, and vanilla and stir until butter is melted.
Pour into baked pie shell and sprinkle lightly with cinnamon.
Bake 35 minutes; center of pie will not be set. Cool pie 1 hour, then refrigerate 6 to 8 hours, or until ready to serve. Pie will set upon chilling. Cover for longer storage.