FYI, this can be used in russian only when talking about a real cake. It doesn't mean "easy" like in english.
GLaDOS: Cake, and grief counseling, will be available at the conclusion of the test.
Iunno, I say piece of cake, but I wrote slice of cake here b/c кусок хлеба would be a slice of bread, so slice of cake should be taken too.
Yeah, you're right, I shouldn't generalize "we" when I mean "I." But yes, my first thought upon reading this sentence was "slice of cake." Much like bread, a piece of it, would be a small chunk, rather than the portion we know as a "slice." I'm assuming that in Russian these details don't matter as much though.
I usually hear ломтик хлеба for a slice of bread. I bet in Russian, the way people usually slice an even piece of bread off the end of the loaf is being distinguished from say the triangular slices of cake and pizza. Good discovery!