We have recessed lighting throughout the house (Commercial Electric 6 in. IC Airtight Recessed Lighting), and recently, I replaced the white baffle trim (Commercial Electric T5) in the bathrooms with Commercial Electric Shower trim (T13). In the process, I noticed that the circumference around the metal recessed lighting can, where it meets the ceiling paint is cracked, and the plaster is coming off. I need to know how best to repair this? The cracks are not big, they are really max 1/2 inch wide and irregular and are unsightly. I am trying to repair this cosmetic damage and also protect the ceiling, as these cracks on the ceiling in bathrooms (over the tub) are a mold-hazard.

I am a complete newbie and would very much appreciate a detailed answer. Thanks.