1. Preheat oven to 350 ̊F. Grease three 8” round cake pans and line with parchment.
2. In a large bowl, whisk to combine wheat flour, almond flour, pumpkin pie spice, baking powder, baking soda, and salt.
3. In a separate bowl, whisk to combine pumpkin puree, stevia, milk, oil, eggs, yogurt, water, and vanilla. Mix flour mixture into pumpkin mixture, just until combined.
4. Divide batter evenly among prepared pans. Bake for 30-35 minutes or until a toothpick inserted comes out clean. Transfer to a wire rack to cool completely.
5. To make frosting, in a blender or food processor, process stevia until it is the texture of powdered sugar. Set aside. In the bowl of a stand mixer fitted with paddle attachment, cream together butter and cream cheese until smooth. Beat in apple sauce, pumpkin pie spice, and vanilla until combined. With mixer on low speed, blend in powdered stevia, 1⁄2 cup at a time, then increase speed to high. Continue beating until smooth.
6. To assemble cake, place bottom cake layer on a serving plate or cake stand. Top with a thin layer of frosting. Repeat with the next two layers of cake and frosting. Use remaining frosting to coat the outside of the cake and decorate the top.