Cream together maple sugar and butter. Add egg and continue beating until lightened in color.
Add corn starch, salt, and cream. Beat until combined.
Pour into unbaked pie shell and bake at 350 degrees for 45 minutes or until center is set. The degree of doneness is up to your personal taste. For a darker, more caramelized pie, bake longer. For a light-colored, barely set pie, decrease the heat to 325 degrees and bake until set.