Rinse banana leaves under warm water and trim away thick edges. Trace the bottom of a 9x13 inch baking pan onto banana leaf. Quickly pass and heat leaves over stove flames for a few seconds or until just softened. Line pan with the leafs, making sure it is intact with no rips. If not using banana leaf, substitute a greased parchment paper.
In large bowl, combine rice flour, sugar, baking powder and salt. Whisk together until well dispersed.
In another bowl, combine coconut milk and butter and stir until blended. Add to rice flour mixture and gently stir until batter is smooth. Add beaten eggs and stir until blended.
Divide mixture and pour into the prepared pan. Bake in a 350 F oven for about 20 to 25 minutes or until golden and toothpick inserted in the middle comes out clean. If desired, place under the broiler for about 1 minute or until nicely charred.