Preheat the oven to 180°C (fan-forced). Line the base and sides of a 28 cm x 18 cm slice tin with baking paper.
Combine all coconut base ingredients in a mixing bowl and mix well with a wooden spoon.
Press the mixture into the tin and spread out evenly. Bake for 12–14 minutes until the base is golden brown.
Remove from the oven and let cool. Reduce the oven temperature to 160°C (fan-forced).
Place all lemon and passionfruit topping ingredients in a mixing bowl and mix well until the mixture thickens.
Spread the topping evenly over the cooked base.
Return to the oven and bake for 15 minutes until the topping is set but with a slight wobble.
Transfer the slice to the fridge to firm up for 2–3 hours.
Remove from the tin and cut into 12 pieces.
