Preheat oven to 175°C / 350°F
Line a 20 cm / 8 inch square tin
Blend all wet ingredients until smooth and fluffy
Add all dry ingredients and fold in gently
Add chocolate and nuts
Pour into tin and smooth the top
Bake for 22–25 minutes until risen but looking slightly underdone
Cool in the tin for 10 minutes
Lift out onto a wire rack
Serve warm for a fluffier texture or refrigerate for a denser fudgier finish
