In a large bowl, combine the rice flour, sugar, salt, and baking powder.
In another bowl, whisk together the coconut milk, water, melted butter, and vanilla extract.
Gradually add the wet ingredients to the dry ingredients, mixing until you have a smooth batter.
Preheat your oven to 350°F (175°C).
Line a baking dish (8x8 inches) with banana leaves or parchment paper. If using banana leaves, you can lightly grease them to prevent sticking.
Pour the batter into the prepared baking dish and smooth the top with a spatula.
Bake in the preheated oven for 25-30 minutes, or until the top is set and a toothpick inserted into the center comes out clean.
Let the Fouti cool in the baking dish for about 10 minutes, then transfer to a wire rack to cool completely.
Cut into squares or slices and serve.
Enjoy your meal!