Preheat oven to 350 degrees F (175 degrees C). Grease an 8x8-inch baking dish.
Whisk rice, evaporated milk, raisins, eggs, white sugar, brown sugar, custard powder, and vanilla extract together in a bowl; pour into the prepared dish. Sprinkle nutmeg over rice mixture.
Bake in the preheated oven until a knife inserted into the center of pudding comes out clean, about 30 minutes.
