…what?
They’re not cakes
They’re not cookies either, really - because they’re made in a tray and cut up into squares.
What are they?
I would call them either a bar cookie, or a dessert bar.
They’re confectionery like Lion bars (except with marshmallow and not chocolate).
Pure joy.
Clearly, they are “treats”.
Ah, ‘treats’ is good.
Cereal bar. 
A slice. Pronounced sloice. The article says Americans would call them bar cookies.
Nope, we call them treats.
…torture designed to torment vegetarians because of the ridiculous scarcity of marshmallows that don’t contain gelatin.
“Yummy”.
That’s what they are.
By the way, you guys are assholes. Yesterday, I got an oatmeal cream pie out of the vending machine because of this place, now I’m about to pay 80 cents for a freakin’ Rice Krispie treat. I hope you guys are happy.
They fall into the general category of partially gelatinated processed puffed grain confections.
hors’ dourves
This American would call Marshmellow Krispie Squares “treats” (actually, Rice Krispie Treats, probably).
A bar cookie to me is what you get if you take a batch of cookie dough, and spread it in a flat pan, bake it and the cut it. And I’d almost never call it a “bar cookie” as opposed to a “bar” with the cookie part understood.
OK, I might call the treats “bars” in a context where having fewer terms was useful “3 people brought cakes, 4 brought pies, and the rest brought bars”, but not ordinarily.
Mangetout, if you had grown up in the American Midwest you would say with complete assurance that Rice Krispie treats are “bars.” Any dessert that is cooked up in a pan and then cut into squares is (are?) bars. Except fudge. The traditional upper midwest church-supper type buffet is: Hot dish (casserole); salad; fruit punch (non-alcoholic, of course); and bars.
Yeah, I was going to answer the OP with “…meat”. Blasted gelatin is hard to avoid. Didja know that bitters, of all things, have gelatin? I got my little bottle of Angostura bitters home a few moths ago, and I was looking forward to many happy evenings of Old Fashioneds when I thought, “What are bitters anyway?” I turned the bottle over, and…let out a stream of curses. Who the *&%$! puts gelatin in something you drink?!
Anyway, to answer the OP, I vote for “treats”. Meaty treats.
It’s not a real Rice Krispie treat unless you buy it at a bake sale.
Jodi has said it best. Though they are a bar cookie, they are specifically a Rice Krispie Treat.
Seconded.
What the hell, guys? I went home last night and made a big batch of snickerdoodles (since fruit pies were out of the way) and it’ll be all the Dope’s fault when my ass expands past the point where I can still stuff it into my pants. MMMMM, Rice Krispie bars.
Yeah, that’s the ticket. Not my fault at all…
In Minnesota “bars” are a category unto themselves and Rice Krispy Treats (or as they’re called up here, “Rice Krispy Bars”) are clearly bars.