Line a 20 cm by 20 cm square cake pan with parchment paper. If you don't have a square cake pan, make a frame out of thick paper, wrap it in aluminum foil, then line it with parchment paper.
Put all of the ingredients in a food processor or mixer and pulse to a thick batter.
Bake in an oven preheated to 200℃ for 15 to 20 minutes. If it doesn't brown, bake for 5 more minutes at 220℃ until golden brown.
Turn over onto a dampened sushi mat, and while it's still hot, tightly roll.
Fix rubber bands in two or three places around the mat, then wrap in plastic wrap. Allow to cool, then chill in the refrigerator for a while.
It's done! It's less sweet than store-bought date-maki. We make this every now and then for regular meals.
Story Behind this Recipe
I was always unable to make date-maki in a tamagoyaki pan, until a friend told me that it's easy to make in an oven. Experimenting with several recipes, I came up with a low sugar, tasty date-maki.
If it doesn't brown, then raise the temperature briefly until it browns. If it cooks at a low temperature for too long, it will turn out dry and crumbly. Roll it up tightly while it's still hot. Otherwise, it will unroll easily.