Take it with a grain of sugar

Unlike the original saying "Take it with a grain of salt", this term is used when you tell someone something heavy or harsh, but you want them to take it as nicely and sweetly as possible (which is where the sugar part comes in).

"Take it with a grain of sugar, but you look like you just rolled out of a grave"
"Take it with a grain of sugar, but your soufflé is terrible"