"Harry Potter" is firmly in the rearview mirror for Daniel Radcliffe.

Since hanging up the wand, Radcliffe has starred in Broadway productions ("How to Succeed in Business Without Really Trying," "The Cripple of Inishmaan") and acclaimed big screen period pieces ("Kill Your Darlings").

What he hasn't done, until now, is play an ordinary modern guy. That changes in the romantic comedy "What If," out Friday.

amNewYork spoke with Radcliffe and his co-star Zoe Kazan about the movie, in which their characters bond over a love for Elvis Presley's beloved Fool's Gold sandwiches (peanut butter, jelly, bacon, butter over a sourdough loaf) and more.

Did you guys try some Fool's Gold sandwiches for research?

Daniel Radcliffe: I don't know if it would qualify as research, but yes. You have to eat a lot during the course of filming and it's pretty good. Elvis was not messing around when he made his sandwiches back then.

Zoe Kazan: I thought it was disgusting. This may be a boy-girl divide here, or maybe it's me not loving things filled with butter.

DR: I'm amazed you don't like it because there's a part of me that goes, 'What is there not to like'?

ZK: Honestly, to me it's the butter on the outside of the bread. I don't want that much grease on my hands.

DR: OK, yeah, I guess I didn't notice that.

ZK: Yeah, I was disgusted by it.

Dan, you've haven't had many chances to just play a regular guy. That must have been welcome?

DR: It was great. It was very, very nice to just have to turn up every day and just to be playing a character living in the real world and not have to worry about anything else. That was very nice. Also, it sounds like a thing that you hear actors who do a lot of visual effects stuff whine on about, but it is nice to do a film without any visual effects. All the tension and the plot and all the story comes from people talking. That was new and unusual for me.

What got you on board, Zoe?

ZK: I thought the script was so good and funny and smart and quick and real. I thought it took a situation that is very relatable and made it funny and understandable from both sides of the situation, from the male and female perspective. And I was struck by how Elan Mastai, the writer, turned so many romantic comedy tropes on their head.

You don't usually find a romantic comedy that treats those two points-of-view equally.

DR: I think there's been a tendency in romantic comedies to be mainly focused on the female story line. I think that comes with a thing that we have in society that is men, I think, find it hard to be vulnerable. For example, any problems in my life or anything emotional, I would be more inclined to talk about that with my friends who are girls than any of them who are guys, just because it's a different dynamic. Yeah, I definitely think there's a difference, but it's nice to have men being vulnerable onscreen.

What's the key to making this genre work?

DR: A lot of that is just people responding to characters who seem real. That they are people who are relatable. People's reaction to seeing something they recognize and identify with onscreen is to be excited rather than some romantic comedies that do feel so unreal they can be kind of alienating.

Did you guys hang out a lot? How important is off-screen stuff when it comes to developing chemistry?

DR: It is important. But I also think, we met once before like three years ago, I think we knew enough of each other at that meeting to know that doing the film would probably be fun together.

ZK: It was like an insurance policy.

DR: I think we are very similar, but [director] Michael Dowse cast the film very well, not just in terms of me and Zoe but Adam [Driver], Mackenzie [Davis] and all those things. You have to give a lot of credit to the writer for the chemistry we have. It's all written. As much as we have to do it and obviously feel natural ? we're getting a lot of credit for Elan Mastai's very good writing.

So can we expect a future Kazan-Radcliffe collaboration?

DR: That'd be brilliant. Yes, yes, you heard it here first. Yeah we definitely would, we've had a great time, so doing something on stage would be awesome.

ZK: But something not romantic. Something where I kill you, or where I turn into a puppy dog ? [laughs]