something is as easy as pie/it is a piece of cake: something is very simple to do or understand
half-baked: incomplete or not thoroughly planned
E.g. The boss would have been approved his new idea, if it hadn’t been so half-baked. Next time, he has to spend more time on preparing it.
As an editor, I get a lot of half-baked stories, and the authors get upset if we don't publish them. They have to make sure their story is complete and thought through.
icing on the cake: an additional benefit
E.g. Today she was promoted to head of the department and as an icing on the care, she also got a raise!
His new girlfriend is not just beautiful but very smart and funny too. What an icing on the cake!
that’s the way the cookie crumbles: it refers to something disappointing that could have been expected as typical outcome, similar to “that’s life”
E.g. No matter how hard she tried to be popular, the new girl was not able to make friends. But, that's the way the cookie crumbles.
Nobody could believe that they chose Nick for the job and not Julie. Ah well, that's the way the cookie crumbles
to get a piece of the pie: to be among those who earn an advantage or reward
E.g. Lazy people want to a piece of the pie too, but they are not willing to work for it.
When the business started making money, everyone wanted a piece of the pie.
to sugarcoat something: to put something in a positive light
E.g. She is not afraid to share her opinions even if they are negative, and she doesn't even try to sugarcoat them.
The governor did not sugarcoat the reality of the tax increases. It’s not what we wanted to hear, but at least we knew exactly what would happen.
to have your cake and eat it, too: to have an unrealistic expectation about accomplishing something, to have it both ways
E.g. If you want more local services, you can't expect to pay less tax. You can't have your cake and eat it too.
He works long hours to pay for their big house and fancy car, but complains that he does not have time for his family. Well, you can't have your cake and eat it too.