Preheat oven to 375 degrees. Mix up pie crust and press into pie pan, place holes in the crust with a fork, bake for 10 minutes. Whisk the sweeteners, water, agar agar, cinnamon and salt in a sauce pan and bring to a boil. Simmer for 5 minutes, or until agar agar dissolves, whisking occasionally. Dissolve the arrowroot in cold water. Whisk the thickener into the simmering pot. After 15 minutes stir in the vanilla, nutmeg, nutritional yeast, maple syrup, sugar and walnuts. Pour filling into baked crust. Allow it to cool and settle for 2 hours, or refrigerate for an hour. Serve at room temperature.