Preheat & prep: Preheat oven to 200°C / 400°F. Line a baking sheet with parchment. Chill butter if needed.
Mix dry: Whisk almond flour, baking powder, salt, and powdered erythritol together in a large bowl.
Cut in butter: Add cold cubed butter and cut into the flour until coarse crumbs with pea-sized butter pieces remain.
Combine wet: Whisk eggs, heavy cream, dissolved espresso powder, and vanilla. Add to dry mix and fold until just combined.
Add chunks: Fold in cacao nibs or chocolate chunks.
Shape: Pat dough into an 18–20 cm disk ~3–4 cm thick. Cut into 8 wedges or stamp rounds. Transfer to baking sheet.
Egg wash & bake: Brush with egg if desired. Bake 14–16 minutes until set and lightly golden. Cool on a wire rack 8–10 minutes.
Serve: Enjoy warm with coffee; store or freeze extras per storage tips.