For the cookie cups, preheat oven to 325F and grease a mini muffin tin (24 mini-muffin capacity).
In a large bowl, whisk together almond flour, erythritol, espresso powder, baking powder and salt.
Stir in butter, egg and stevia until dough comes together.
Form by hand into approximately 1-inch balls and place dough balls into prepared mini-muffin tin. This recipe will make exactly 24 so if you've made your balls too big or too small, go back and redistribute the dough.
Press the dough into the bottom and up the sides of each mini-muffin hole. Bake 10 to 12 minutes, until edges are lightly brown and cookie cup is puffed up a bit.
Remove from oven and use the end of a wooden spoon to gently create a nice well in the center of each cookie cup. Let cool.
For the filling, ship cream with powdered erythritol until it forms stiff peaks. Stir in coffee liqueur and stevia extract.
Gently fold in room-temperature mascarpone. If it separates and gets clumpy, beat in guar gum ¼ teaspoon at a time until comes back together.
Spoon or pipe filling into cooled cookie cups. Sift cocoa powder over top and refrigerate 20 minutes to set.
Serves 12 (2 cookie cups each). Each serving has 5.5 g of carbs and 2 g of fiber. Total NET CARBS = 3.5 g.