Preheat the oven to 350°F. Prepare a 24-cup muffin pan with liners or a light coating of butter.
In a large mixing bowl, whisk together the almond flour, baking powder, sugar substitute, and cocoa powder. If the almond flour and cocoa are lumpy, sift them first.
Add one egg at a time, beating well after each addition.
Stir in the melted butter, vanilla extract, and cooled coffee until the batter is smooth and well-combined.
Divide batter equally among the prepared muffin cups, filling each about 2/3 full.
Bake for 10-12 minutes, or until a toothpick inserted in the center comes out clean—check at the 10-minute mark to avoid overbaking.
Remove from the oven and allow the cupcakes to cool in the pan for 5–10 minutes.
Transfer the cupcakes to a wire rack and let them cool completely (30-60 minutes) before frosting.