Caution: This is not an easy recipe, unlike most of the other recipes on this site. Please read each step carefully before proceeeding. No, there is no mistake in the recipe - it works, as long as you follow each step!
In my previous post about Japanese food , I talked about what makes up a typical Japanese meal, which applies to breakfast, lunch and dinner. There's a fourth meal that is very much a part of Japanese food life - oyatsu. Oyatsu is snack time, and it's usually eaten at 3 in the afternoon.
Oyatsu consists of a drink, which is usually tea for adults and milk or soft drink for kids, and a sweet or savory snack. A lot of the Japanese snack industry is geared towards oyatsu items. It's lighter than an English afternoon tea - it's more like elevenses (the snack that was traditionally consumed around 11 in the morning in England). It helps to keep hungry kids going until dinner time, and provides a good excuse for the adults to take a break.
One of my favorite oyatsu snacks growing up in Japan was kasutera or castella, and it remains a favorite even now. The origins of kasutera, a light sponge cake that is most often flavored with honey, are in either Portugal, Spain, or both. The first recorded Westerners to ever land on Japanese soil were Portuguese missionaries. They were eventually kicked out along with other Westerners, when the Tokugawa government decided to close off the country to most outside contact in the 17th century. But they did leave their legacy in the form of additions to the language  and to the cuisine. (Wikipedia page on kasutera's history .)
Kasutera is a kind of sweet that is hardly ever baked at home in Japan. It's available in all price ranges, from mass-produced plastic wrapped kinds that you can buy in any supermarket to expensive "gourmet" labels. Perhaps because the Portuguese influence was the strongest there, the southernmost main island of Kyushuu has some of the best kasutera makers.
The best known mass-produced kasutera brand is Bunmeido. This is the one we ate all the time when I was growing up. I can still remember the jingle, which didn't make sense then and still doesn't make sense now -
kasutera ichiban, denwa wa niban,
sanji no oyatsu wa Bunmeido
(Kasutera no.1, telephone no. 2, 3 o'clock snack is Bunmeido)
This jingle was sung by a line of teddy bears doing the can-can. (Here's a YouTube video  where you can hear the jingle, though those dudes are somewhat less cute than the original teddy bears.)
I used to work for a company run by a family from Nagasaki. Although my boss was very difficult to deal with in many respects, he almost redeemed himself in my eyes by always bringing a block of delicious kasutera with him whenever he flew back from Japan.
A good kasutera is moist, with a very fine texture, and is very light. It should have a dark brown and sugary top and bottom - the sides are usually cut off, exposing the yellow crumb. It is sweet yet not cloyingly sweet. It does not have a speck of oil in it - no butter, no margerine, no shortening. Yet it is very rich. The best flavoring is honey, though other sugary syrups are often used too. There are variations, like matcha (green tea) or chocolate flavored, but I prefer the traditional honey flavor.
A slice of kasutera is the perfect accompaniment to a cup of hot green tea, unsweetened of course.
If I lived in Japan, frankly I don't think I would make my own kasutera because of all the delicious brands out there. It's also not that easy to make, since it uses the classical cake making method of whisking together whole eggs and sugar in a bowl over hot water until it's thick. But it's hard to get good kasutera here, so on occasion I haul out my electric whisk and get going. The results are usually worth all the effort. The only bad thing is that the kasutera disappears so fast.
Please note that the measurements for the original Japanese recipe that I've adapted for this one is in metric, and unlike many other of my recipes it's best to be pretty precise in your measurements for this. So I have given amounts in grams/ounces rather than cups.
Before you proceed: Unlike most of the recipes here on Just Hungry, this one is not easy to execute. If you are a cake baking novice, you may want to tackle something simpler before trying this. Please read through the instructions completely.
Equipment and other supplies:
Preheat the oven to 170°C / 340°F, or 150°C / 300°F if you're using a convection oven.
Cut the parchment paper so that it's large enough to fit the bottom and sides of the cake pan with a little excess. Fold it in until it completely covers the bottom and sides, leaving a it hanging over. (To make it stick to the pan, smear a little butter or shortening on the pan first.) Sprinkle a little sugar over the bottom, on top of the paper.
Fill the pot with water and bring to a boil, then turn off the heat.
Mix together the milk and 4 tablespoons of honey - you may need to heat up the mixture for a few seconds in the microwave.
Measure the flour and sugar. Double-sift the flour. (That means passing it through your sifter or sieve twice.)
This next step is critical to the success of this recipe. Most of the people who have had problems with it have failed at this stage. I highly recommend having at least a handheld electric whisk for this. A stand mixer may be even better, if you can fit it with a 'water jacket' to keep it warm. Break the eggs into the bowl and whisk. Add the sugar. Start whisking this while holding the bowl over the pan of hot water. As soon as the mixture feels lukewarm to the touch, take it off the water and continue whisking. If it cools down again, put it back on the hot water pan to warm it up. You get the best texture if you stick to the lowest setting on your electric whisk, or whisk by hand, but you'll be at it for a long, long time. I usually turn up my electric whisk to about setting 2 or 3 until it starts to thicken, and then do the rest of the whisking at setting 1 to have small bubbles at the end. Either way though, you'll be whisking for a very long time. (Give it at least 15 minutes with an electric whisk, and a lot longer by hand.)
When you are done the batter will be thick enough to form soft peaks when you draw up your whisk. If you write your initial on the surface with the whisk, it should stay there long enough for you to read it before it disappears.
Whisk in the milk and honey mixture. Add the flour with your hand whisk a tablespoon at a time, beating until there are no pockets of flour.
Pour the batter into the pan up to the top. (see notes about what to do with any leftover batter.) Put in the oven and bake for about 50 minutes or until a skewer stuck in the middle comes out clean.
In the meantime, mix together the 1 tablespoon of honey and a little hot water, to make a glaze.
As soon as the cake is out of the oven, brush the top with the honey-water mixture.
When it's cool enough to handle but still warm, lift it out of the pan, paper and all, and put into a plastic bag. Seal the bag and put into the refrigerator, for at least several hours. This step is critical to ensure the kasutera has a moist texture. If you let it cool to room temperature before putting it in the plastic bag, it will end up a bit dry.
To serve, use a very sharp knife to make clean cuts. Cut off the sides (cook's treat) and make small, neat slices - one or two per person. Serve with hot or cold unsweetened tea.
Please note that I'm no longer responding to "This recipe doesn't work!" comments. The recipe has been up here for years and it has worked for most people. Again, please be sure to follow all the steps carefully. Or, try another, easier recipe on this site.