Preheat oven to 180*c and line a square baking dish (mine is 20cm) with greaseproof paper.
Add flour, butter and sugar to a large mixing bowl and process with your fingers until it forms a rough, sandy texture. Press into the baking dish and bake for 20 mins, until golden.
While the shortbread is cooling, make lemon curd by adding all curd ingredients apart from the tofu to a small pan over a medium heat. Bring to the boil and stir for 4-5 minutes until it starts to thicken.
Remove from the heat and add soft tofu. Blend using an immersion blender or in a food processor until smooth and creamy. Pour on top of the shortbread and allow to chill in the fridge for 3 hours, or until the top has set. Slice into bars and enjoy immediately or freeze for up to 2 weeks.