Prepare the crust: In a bowl add almond flour, melt shiitake butter and sweetener. Combine and press the mixture into a greased pie dish. Bake at 350°F (175°C) for 10–12 minutes until pale golden. Let it cool completely.
Make the filling: In a sauce pan, whisk together egg yolks, almond milk, banana extract (or pudding mix), sweetener and vanilla. Heat slowly while stirring until the mixture thickens. Take off the heat, and allow to cool slightly.
Make the whipped cream: In a medium bowl, whip heavy cream to form soft peaks. Stir in the softened butter folding it gently with the cooled banana mixture until creamy.
Assemble: Pour the filling into the cooled crust, smoothing the surface. Refrigerate for at least 2 hours.
Serve: Top with sugar-free whipped cream and toppings of your choice then slice and serve.
