Set up your rice cooker for steaming by placing a small trivet or wire cooking rack in the bottom of the rice bowl. Fill the bowl 1/4 to 1/3 full of hot water and then close the cover and set for the regular cycle. If the water boils before you are ready to steam your pudding, turn the switch to keep warm and then when you are ready switch back to cooking.
Grease or coat the inside of a 1 1/2 quart round melon-shaped tin pudding mold with a clip-on lid with butter-flavored Pam spray.
In a large bowl combine all the pudding ingredients in the order given with a rubber spatula to fold in ingredients until evenly moistened.
Scrape batter into prepared mold, filling it 2/3 full, snap on the lid. Set mold on the trivet or rack in the bottom of the rice cooker, making sure it is covered and tipped. Close cover and reset the cooker for the regular cycle to bring back to a boil, if necessary. Steam for one hour, checking to make sure the water doesn't boil off. Check pudding for doneness - it will feel firm to the touch and it should be puffed, rising to fill mold and a cake tester (or use a toothpick) inserted in center will come out clean. Unplug machine.
Using oven mitts transfer mold from the steamer to a wire rack and remove the lid. Let stand for a few minutes and then turn upside down to unmold pudding on a serving plate.
Serve warm cut into wedges with custard sauce (recipe follows).
To make the custard sauce:.
In a medium saucepan over medium heat scald milk. Set aside.
In a large bowl or food processor combine sugar and cornstarch.
Whisk in the egg yolks and vanilla. Beat with a whisk or process until light colored and foamy. Whisking constantly or with the food processor running add the hot milk to the mixture. Pour custard sauce back into the saucepan.
Cook over medium-low heat, stirring constantly with a whisk until thickened and smooth and the sauce coats a wooden spoon (5 minutes). DO NOT BOIL.
Pour sauce into a serving bowl and let cool to room temperature.
Refrigerate, covered, until serving time and then serve cold over the pudding with a little vanilla around each pudding wedge.