1 box mochiko*
Beat eggs, sugar. Add melted butter. Add the baking powder. Mix in as much mochiko as possible before adding any further liquids (so as to prevent the butter from separating from the rest of your layers and giving you a greasy butter mochi).
Add the rest of the liquids. If after you add the liquids it looks like the butter has separated from the rest of the layers (i.e. you see a slight oil layer), you can just beat rapidly and the oil will eventually re-emulsify into the mix.
Bake at 350F uncovered for 45min to 1h. Should have golden crust when done, bounces back when you push on it (i.e. not liquidy) and inserted toothpick comes out clean. Let cool competely before cutting (plastic knives seem to stick less.)
Makes 1 9"x13" pan.
(Courtesy of my cousin and her mom)
*mochiko is Japanese sweet rice flour; you can get it at Asian markets, Safeway at San Antonio Shopping Center, or Whole Foods (I haven't found it at the other Safeway on El Camino, or the Secret Safeway); can also use Chinese glutinous rice flour