Set your oven to 180°C (350°F). Place two small round silicone cake moulds or cases on a baking tray.
In a medium bowl, whisk together the egg, ricotta, maple syrup, and vanilla extract until smooth and creamy.
Sift in the cocoa powder, then add the polenta and baking powder. Mix until well combined.
Gently stir in the chestnuts.
Divide the batter evenly between the two prepared moulds. Bake for 20 minutes, or until a toothpick inserted into the centre comes out clean.
Air fryer option: Bake at 190°C (375°F) for about 15 minutes, checking for doneness toward the end.
Enjoy warm or at room temperature. For a special touch, top with Greek yogurt, a drizzle of maple syrup, and a few extra chestnut pieces.