Keep the cobs in their husks and, if the husks are dry, give them a quick rinse under cold water.
Place 1-4 cobs of sweetcorn (still in their husks) in the microwave. For 1-2 cobs, cook on full power for 4-5 minutes; for 3-4 cobs, cook on full power for 8-10 minutes, adjusting for your microwave's power.
Carefully remove the hot cobs and leave them to rest for 2-3 minutes to allow the steam to finish cooking.
Peel back and discard the husks and silk, removing any remaining silk with a paper towel if needed.
Spread softened butter over the hot cobs and season with salt and freshly ground black pepper. Serve straight away.