Combine cassava, coconut milk, 1/2 the sweetened condensed milk, macapuno, and sugar in a large saucepan over medium heat. Bring to a boil, stirring constantly. Transfer to a 9x13-inch glass baking dish.
Bake in the preheated oven until almost set, about 40 minutes. Remove from the oven; spread remaining sweetened condensed milk on top. Continue baking until top is browned, about 20 minutes.
Cool to room temperature or refrigerate before serving, about 1 hour.
