For the filling, combine sweetener and cinnamon in a small bowl. Set aside.
Preheat oven to 325F and line a baking sheet with parchment paper.
In a large bowl, whisk together almond flour, sweetener, baking powder, xanthan gum, and salt. Stir in 1/4 cup butter, egg and vanilla extract until dough comes together.
Turn dough onto prepared baking sheet and divide in half. Form each half into a rectangle about 10 by 4 inches. Make sure both halves are similar in size and shape.
Sprinkle one half with about 2/3 of the cinnamon filling. Top with the other half of the dough and seal the seams and smooth the top.
Bake 25 minutes or until lightly browned and just firm to the touch. Remove from oven and brush with remaining melted butter, then sprinkle with remaining cinnamon mixture. Let cool 30 minutes and reduce oven temperature to 250F.
Using a sharp knife, cut log into about 15 slices (a straight up and down motion works better than sawing back and forth).
Place slices back on baking sheet cut-side down and bake 15 minutes, then flip over and bake another 15 minutes. Turn off oven and let sit inside until cool.
For the glaze , whisk powdered sweetener with cream and vanilla extract until smooth. Drizzle over cooled biscotti.
Serves 15. Each serving has 4 g of carbs and 2 g of fiber. Total NET CARBS = 2 g.133 Calories; 12g Fat (79.0% calories from fat); 4g Protein; 4g Carbohydrate; 2g Dietary Fiber; 27mg Cholesterol; 113mg Sodium.