Activate the yeast: Mix instant yeast with 2 tbsp warm coconut milk and 1 tsp sugar. Let sit for 5–10 minutes until foamy.
Whip eggs and sugar: In a mixing bowl, beat eggs and sugar until pale and slightly thick.
Combine dry and wet: Add sifted flour gradually, stirring gently. Pour in the yeast mixture, mashed bananas, remaining coconut milk, banana essence (if using), and melted butter. Mix until smooth and well combined.
Ferment: Cover the bowl and let the batter rest for 30 minutes. The surface should look slightly bubbly.
Cook: Heat a pukis mold pan (or alternative pan, see notes) and lightly grease with butter. Pour batter until ¾ full. Cover and cook until half set. Sprinkle with chopped cashews, then cover again and cook until golden and fully set.
Remove from the mold and serve warm.