Remove and save broad corn husks, discard damaged pieces and remove silk. Wash the husks and soak in warm water until flexible, about 15 minutes. Cut corn kernels off the cobs and weigh 1,000 g. Drain the husks before filling.

Pulse the kernels in a food processor in batches until finely chopped and moist, with small corn pieces remaining. Do not add water. Transfer to a mixing bowl.

Beat the softened butter and sugar together, then stir into the corn with the cornmeal, baking powder and salt. Rest for 10 minutes while preparing the steamer. The mixture should hold a soft mound on a spoon rather than pour like a drink. If unusually watery, wait another 5 minutes for the meal to hydrate; do not wrap a liquid filling.

Add water below the basket without letting it touch the tamales. Line the basket with spare husks and bring the water to a gentle simmer. Keep additional water hot for replenishing.

Divide the mixture evenly into twelve portions. Place each portion on the broad part of a husk, leaving borders for folding. Bring the sides together around the mixture and fold the narrow bottom end upward, leaving the top open. Overlap two husks if needed. Stand the wrapped uchepos upright in the basket, supported by extra husks, without packing them tightly.

Cover with spare husks and the pot lid. Steam at a steady gentle simmer for 60–75 minutes, checking the water level about every 20 minutes and carefully adding hot water as needed. Test one: its center should be set and the wrapper should peel away fairly easily. If wet batter clings to the husk, steam another 10–15 minutes and check again.

Turn off the heat and rest the uchepos in the covered steamer for 10 minutes. Open the lid away from your face, remove with tongs and serve warm. Peel off the husks before eating.