Lightly grease and line a 15 cm round or 15 × 15 cm square baking dish.

Peel and core the apples, then cut them into small pieces.

Blend the apples and eggs until completely smooth.

Add the optional vanilla and blend briefly.

Sift the cocoa powder and add it in three stages, blending and scraping down the sides between additions.

Check the batter. It should be thick and smooth. If the blender cannot process it, add 15 ml water at a time.

Transfer the batter to the prepared dish and smooth the surface.

Bake for approximately 30 minutes, until the centre is set but still moist.

Cool in the dish for 15 minutes before lifting out.

Cool completely for clean slices or serve slightly warm for a softer texture.

Cut into eight portions and serve.