Preheat oven to 160C (325F), Gas Mark 3. Grease two rectangular baking tins about 20×30 cm (8×12 in) and 2.5cm (1 in) deep.
Peel the cassava, rinse thoroughly in cold water to remove the starch and pat dry, then grate finely into a large mixing bowl.
Place 2 whole eggs and 2 egg whites in a bowl and beat together. Place the 2 egg yolks in a separate bowl.
For the topping, add one-third of the can of condensed milk and two-thirds of the can of coconut milk to the egg yolks and beat together well.
Add all the remaining ingredients (except the egg yolk mixture) to the cassava bowl and mix together well, making sure you add the remaining condensed milk and coconut milk from the cans. Pour the mixture into the greased tins and bake for 30–40 minutes or until there is no liquid on top.Remove the cakes from the oven and spread the topping mixture evenly over both cakes, then increase the oven temperature to 180C (350F), Gas Mark 4, and bake for a further 20–30 minutes until they start to brown a little and the liquid has disappeared.
Leave the cakes to cool completely in the tins before serving. They will keep in the fridge for up to 3 days.