Is it a problem if hot milk splashes on a meat counter?
This is a problem. Because the counter is meaty, the hot milk will render it treif due to the mixing of meat and milk. This can be a problem for the future if hot food is placed on the counter – in particular if this is done within 24 hours of the spillage.
In order to rectify the problem you should pour boiling water onto the counter, which is effectively a means of Kashering the counter. The boiling water should be poured from a bubbling source (it is best that the kettle should be plugged in). Lechatchilah, the water should be poured onto a hot source on the counter, so that the water remains hot after it falls on the counter.
Befor the Kashering procedure the counter should be washed with soap and water and dried. It is likewise best to wait 24 hrs before Kashering.
See Sefer HaKashrus Chap. 1