Preparation method

1. Preheat oven to 180°C.
2. Grease and line a 20cm square cake pan with baking paper.
3. Place butter and ⅔ of the chocolate into a saucepan, and stir occasionally over a medium-low heat until melted and smooth.
4. Remove saucepan from heat.
5. Stir sugar and vanilla into chocolate mixture.
6. Add eggs, and stir until combined.
7. Sift flour over mixture and stir until combined.
8. Add raspberries, lemon zest and the last of the chocolate, and gently stir through mixture.
9. Pour into prepared cake pan.
10. Bake for 35 minutes, or until set.
11. Cool blondie in pan.
12. Remove from pan, dust with icing sugar and cut into blocks.