Praise be to Allah, and peace and blessings be upon the Messenger of Allah and his family.
It is not permissible to sell cakes, desserts or other food to one who will drink alcohol with it.
It says in Kashshaf al-Qina‘ (3/182): It is not valid to sell food, drink or aromatics to someone who will drink intoxicants with them, or to sell vessels and the like to someone who will drink intoxicants from them, or to sell eggs, walnuts and the like to one who will gamble. End quote.
If these types of cakes or deserts are usually eaten with alcohol by those who drink it, it is not permissible to sell them to them, or to the pub or bar which will serve them to those people, because that comes under the heading of helping in sin. Allah, may He be exalted, says (interpretation of the meaning):
{And cooperate in righteousness and piety, but do not cooperate in sin and transgression. And fear Allah; indeed, Allah is severe in penalty} [al-Ma’idah 5:2].
But if these people do not eat these cakes and desserts with their drinks – rather they are things that are sold in the pub for those who want them, like water, juice and other permissible things – and they have no connection to the drinking of alcohol, then in that case it is permissible to sell them.
If you are not sure about that, then to be on the safe side you should not sell them to them.
And Allah knows best.