have cake and eat it

have your cake and eat it (too)

to have or do two good things that it is usually impossible to have or do at the same time He wants to have his cake and eat it. He wants the security of marriage and the excitement of affairs. You can't have your cake and eat it. If you want better local services, you have to pay more tax.
See the icing on the cake, take the cake
See also: and, cake, eat, have