Zaftigs is a Jewish deli in the most liberal sense of the word. (Jew-ish, more like.) They serve blintzes, knishes, half-sour pickles, and smoked fish platters, but also chicken Caesar wraps, Cobb salads, and bacon cheeseburgers (with Russian dressing, of course). To me, that makes Zaftigs more of a diner than a deli.
In fact, it's pretty well known that most of the people who crowd this Coolidge Corner institution for weekend brunch aren't here for bagels and lox or pastrami sandwiches. They're here for the short-order house specialty: banana-stuffed French toast ($9.95).
The gooey banana filling is what people gush over, but this dish wouldn't have the food appeal that it does if the kitchen wasn't following the cardinal rules of French toast cookery. First, they use challah. That's key not just because of the Jewish thing, but because, in my opinion, the only French toast worth eating is made with soft, rich, eggy breads like challah, brioche, or Portuguese sweet bread. (All due respect to humble pain perdu, of course.)
Second, they cut the bread thick. This slab measures a good two inches up from the plate, meaning the ratio of plush interior crumb to crust is really high.
Third, they don't skimp on the batter. For the sake of emphasis, I'll say that there's nothing worse than French toast that hasn't sufficiently soaked in the egg-milk mixture, and cooks up dry and chewy. This version sops up just enough of the dip, which happens to be spiked with bourbon and vanilla. Goes hand-in-hand with the banana goo in the middle.
Fourth—and this is literally just gravy—they serve it with soft, salty date butter and real maple syrup. (It also comes garnished with fresh berries, but they tend to be less than sweet, so I usually scrape them off.) Frankly, the toast itself is so good that it doesn't need all the fixin's, but it doesn't hurt it either. (Note: That date butter is good enough to eat on its own, and comes with several other carb delivery systems, including pancake specials and the grilled banana nut bread.)
And then there's that gooey banana filling: warm and a little boozy, which amps up the fruit's natural flavor. Some takes on stuffed French toast go the croque monsieur route, sandwiching the filling between two slices of bread.
I prefer the Zaftigs' approach, where the center of the bread is scooped out and replaced with mashed bananas. When you tuck into it, the effect resembles a volcano cake, the near-molten filling gushing out like lava.