don't have to / can't

I wonder if "can't" would be a possible choice as well. No,

Hi Yoong,
Why NOT?

imantaghaviHi Yoong,Why NOT?

You can't.

Hi enoon,
I'm not sure, but I think I've heard something in that vein in movies.
Here is an instance from Modern Family (american series):
"Hey Cam, you can't just call a girl and let her go alone ..."

Cheers,

Iman

imantaghavi " You don't have to / can't use cream in this sauce, but it makes it much tastier."

From a syntax persepctive "don't have to" is the only correct answer: You can use cream in the sauce. It adds to the flavor. But you don't have to. "Can't " may be possible in other context.

I see what you mean, but that would make your original sentence more like, "You can't use cream in this recipe and have it be edible."

Sorry enoon to take your time, but I need more clarification.I don't buy it.

imantaghaviSorry enoon to take your time, but I need more clarification.I don't buy it.

I think it's me who needs clarification. What are you trying to say about the cream and the sauce?

imantaghaviI don't buy it.

imantaghavi,
You posted a context and asked if "can't " is possible. Well, anything is possible but the question becomes; will it make semantic sense? Sometimes what looks grammatically sound may not make sense.

Here is the clarification enoon: Generally speaking we don't add cream to the sauce, but here in this particular case it's mentioned that if you do so it makes it tastier.
that's all I wanna convey with the modal.
Now which of them would be possible or better?