Preheat oven to 350 F.
Whisk together 1 cup maple sugar and 1/4 cup all-purpose flour until the mixture is smooth. Add the whipped cream.
Whisk the mixture together until it is completely smooth. The filling will be a watery consistency.
When the maple-cream filling is smooth, pour it into the pie shell. Bake the pie for 45 minutes at 250 degrees F.
Cool until room temperature (filling will set as pie cools).
If you choose the walnut option, sprinkle your walnuts evenly over your pie shell before you pour your maple-cream filling.
Note: if you are unable to find maple sugar you can use 1/2 cup light brown sugar with 3/4 cup of pure maple syrup.