Dice the sweet potato and microwave until tender. Divide in half and roughly mash half.
Bring the margarine and eggs to room temperature. Cram the margarine.
Add the sugar in about 5 batches, mixing well between each addition. Mix well to incorporate air until the mixture becomes pale.
Beat the eggs in a separate bowl. Add to the mixture from Step 3 in about 5 batches, combining well to ensure they don't separate.
Add the sifted flour and baking powder at once as well as the mashed potato from Step 1 into the bowl from Step 4. Add in the diced potato too and fold in with a rubber spatula. Reserve some of the diced potato for the topping.
Pour the mixture into the pan and drop it onto the table several times to remove air bubbles. Make the middle part sink a little to give it a nice finish.
Top with the reserved potato and sesame. Bake for 35 minutes in the oven preheated to 170°C.
Insert a skewer and if it comes out clean, it's done!
Story Behind this Recipe
I made this simply because I just wanted eat a pound cake with sweet potato. Enjoy the other variations too. Tea Version: Recipe ID: 886467. Banana Version: Recipe ID: 995260.
Make sure not to let the margarine sit for too long. Add the egg in 5 batches, otherwise it'll curdle in the batter (I know from past experience).