✓ Preheat oven to 175°C / 350°F and line an 8‑inch square pan with parchment paper.

✓ Whisk almond flour, coconut flour, cocoa powder, erythritol, and baking powder together in a large bowl until uniformly combined.

✓ In a separate bowl, beat the three eggs until pale yellow and slightly frothy.

✓ Stir melted butter (or coconut oil) and vanilla extract into the beaten eggs.

✓ Pour the wet mixture over the dry ingredients and fold with a rubber spatula until a thick batter forms.

✓ Spread the batter evenly in the prepared pan, smoothing the top.

✓ Bake for 20‑25 minutes, or until a toothpick inserted near the center emerges with only a few moist crumbs and edges are set.

✓ Rotate the pan halfway through baking for even browning.

✓ Remove the pan and let the brownies cool in the pan for 10 minutes.

✓ Transfer the slab onto a cutting board and cool completely for another 15 minutes.

✓ Cut into 12 even squares, wiping the blade between cuts.

✓ Serve at room temperature, optionally dusted with cocoa powder or drizzled with sugar‑free dark chocolate.