Combine oatmeal and pineapple juice in a mixing bowl.
Stir to mix.
Allow to rest for 10 to 15 minutes.
Add baking powder, baking soda, and egg.
Stir vigorously with a spoon.
Then stir in flour.
Transfer to a greased 9 in. (23 cm) round baking pan.
Bake at 350°F (175°C) for 25 to 35 minutes or until pick inserted in middle comes out clean.
Remove from oven.
Sprinkle top with aspartame sweetener.