Salvaging a cheesecake that's oozing butter
I would suggest using a bit of simple syrup or maple syrup instead to melt the chocolate, if you want the taste of butter, add a little bit of flour to the butter first when melting it to make a little bit of a light roux. 

The problem is the chocolate and butter for sure will separate at the temp that a cheesecake bakes at, there's nothing for the butter to cling to.