Wouldn't it be eat your cake and still have it?

The idiom is generally phrased "have your cake and eat it too" but yeah that's rather confusing. The way you said it is how I actually understand it in my head.

I think the way ~~English~~ Common has evolved doesn't help either, because "to have" is now synonymous with "to eat" in the context of food, but I don't think it was that way when the idiom was coined. It's actually about 500 years old according to Wikipedia.