I took Joe H's advice from a Del Ray post infra and hunted down Neilsen's. This is excellent custard and for me, much closer than Milwaukee Frozen Custard in Chantilly (though a small hike from College Park). I also like the ambiance better than Del Ray Dreamery, but that's only my opinion as Im not as 'artsy' as others (no disrespect to Del Ray). All three places have really good custard, but I think Neilsen's gets my vote.
It's located on Church Street just off of Lawyers Road and just up Church from the Vienna caboose on the W & O D trail.
Per the kid in the store, there are locations in Colorado, Utah and Arizona and all are family controlled.