01 - Lightly grease the inner bowl of the rice cooker with butter or nonstick spray, ensuring full coverage for easy release.
02 - Add flour, sugar, baking powder, and salt to a large mixing bowl. Whisk thoroughly to distribute leavening and seasonings evenly.
03 - Beat eggs in a separate bowl. Whisk in whole milk, vegetable oil, and vanilla extract until fully blended.
04 - Pour the wet mixture into the dry ingredients. Stir gently until just incorporated. Fold in chocolate chips or chopped nuts, if desired. Avoid overmixing to prevent a dense texture.
05 - Transfer batter to the prepared rice cooker bowl and smooth the surface with a spatula.
06 - Close the lid and select the 'Cook' function. Bake for 40 to 50 minutes, or until a toothpick inserted in the center emerges clean. If the cooker switches to 'Warm' before completion, wait five minutes and restart 'Cook' as necessary.
07 - Let cake cool in the rice cooker for ten minutes. Carefully remove and transfer to a wire rack to cool completely before slicing and serving.