Preheat oven to 350°F (175°C). Line a loaf pan with parchment.
Whisk almond flour, eggs, oil, sugar substitute, and baking powder into a soft dough.
Combine melted chocolate, oil, cocoa powder, and sugar substitute for the filling.
Roll the dough between two sheets of parchment into a large rectangle.
Spread the chocolate filling evenly over the dough.
Roll the dough up tightly from one long side into a log, then twist it in half lengthwise, keeping the cut sides facing up.
Transfer to the prepared pan, twisted side up. Chill 15 minutes.
Bake 30–35 minutes, until set and lightly browned.
Cool completely before slicing.