In a medium bowl, whisk together the almond flour, cocoa powder, and sweetener. Add melted butter and stir until the mixture clumps together.
Press firmly and evenly into bottom and up sides of prepared tart pan. Refrigerate until filling is ready.
In a small pan, combine cream, almond or cashew milk, and butter. Bring to a full boil and then remove from heat.
In a blender, combine unsweetened chocolate, cocoa powder, sweetener, and espresso powder. Pour in scalded cream mixture and blend until smooth.
Add eggs and blend again until smooth (*if you are concerned about the eggs, use pasteurized shell eggs such as Safest Choice). Pour into chilled crust and chill until firm, at least 1 hour. Gently press the tart pan from the bottom to remove the sides and place on a serving platter.
Beat whipping cream with sweetener and vanilla until it holds stiff peaks. Spread over mousse to the edges of the tart.
Using a cheese grater, shave the dark chocolate over the whipping cream. Let set a bit in the refrigerator before serving.
Serves 12. Each serving has 3.91 g NET CARBS.Food energy: 359kcal Total fat: 33.46g Calories from fat: 301 Cholesterol: 122mg Carbohydrate: 7.95g Total dietary fiber: 4.04g Protein: 6.64g