I don't have the biggest sweet tooth, so when a dessert sticks with me—when I can't shake the memory of its flavor days or weeks later—it's worth taking notice. The dessert that's currently captivated me is this buckwheat custard.
Last month, I went to Japan on a very belated honeymoon. My wife, Kate, and I took a detour to Echizen in Fukui Prefecture to meet a friend who'd offered to take us around for the day. As it turns out, Echizen is a major soba-producing area, the land around it dotted with fields that grow buckwheat, as well as countless soba restaurants transforming that buckwheat into soba noodles. At one of those restaurants, Kura Soba Kodo, we had buckwheat custards for dessert, and I was instantly hooked.
The star ingredient in these custards is soba-cha, which is roasted buckwheat that's typically used for brewing tea (cha means "tea" in Japanese). You can find it at well-stocked Japanese groceries, good tea shops, or online.
It's not uncommon to get a hot cup of soba-cha at the end of a meal at a Japanese restaurant, but if it's not something you're familiar with, I'd describe its flavor as nutty and sweet, almost like chestnuts, with deep woodsy and toasted notes. As you can imagine, it's a flavor that pairs beautifully with cream, just as chestnuts do, adding a savory, earthy note while still acting as a perfect partner to something sweet.
In Japan, these soba-cha custards are called soba purin, which is the Japanese adaptation of the English word "pudding." (Hat tip to Stella Parks, one of our resident Japanophiles, for helping me track down the "purin" lead.) A quick internet search revealed that recipes rely variously on eggs or gelatin: eggs to make a custard version, and gelatin to make something more like panna cotta.
I tried the recipe both ways, and my clear preference was for the eggy custard version, which is richer by far than the one set with gelatin. Once I narrowed it down to that, I again chatted with Stella, our baking wizard, to pick her brain about her preferred way of making custards like this. (As you can see, she played an integral role in this recipe.)
Here's what I ended up with.
I start by steeping the soba-cha in hot cream for about five minutes—more than enough time for its flavor to infuse into the cream. Then I strain out the buckwheat seeds, top up with more cream to account for any that was absorbed by the buckwheat, and proceed with making the custard.
To make the custard, I whisk egg yolks with sugar, then slowly whisk the hot soba-infused cream into them. This is a process called tempering—by slowly adding the hot cream to the yolks, instead of the reverse, you gently warm the yolks so that they don't seize up and scramble as soon as they hit the cream. It's just some insurance against a worst-case scenario.
I then heat the mixture to 140°F (60°C), remove it from the heat, pour it through a fine-mesh strainer (just in case any egg has scrambled, though it's pretty unlikely any will—it's also nice to remove the stray chalazae), and divide it among ramekins. You need to stir and scrape the pot the entire time the custard mixture is heating up, lest any of it that's near the pot's surface overheat and set. Your best bet while doing this is to use a flexible silicone spatula, which can mold itself to the contours of the pot, leaving no patch untouched. If possible, you should also use a saucier, which is a saucepan with curved sides: The gentle slope makes it easier to stir and scrape, unlike a straight-sided pot with a hard right angle at its base.
The ramekins go into a larger baking dish, and the whole thing goes into a 300°F (150°C) oven; boiling water poured into the baking dish acts as a hot water bath, buffering the custards against the oven's strong heat. I recommend adding the hot water after you've set the baking dish on the oven rack, since you're less likely to slosh it around that way.
After about 45 minutes, the custards should be just set. Let them cool in the baking dish, then transfer them to the fridge to chill completely. At this point, they can be held for at least a few days, making them an excellent make-ahead dessert.
Whenever you're ready to serve them, just pull them from the fridge and top with whipped cream and a small sprinkling of soba-cha grains. These are so good, you may want to just load your fridge with them so you have a constant supply at the ready. Like I said, I don't have much of a sweet tooth, and even I'm tempted to keep them on hand from now on.