Whip the eggs in a double boiler until soft peaks form. Preheat the oven to 320°F/160°C.
Add the kuromitsu and matcha to Step 1 and mix well. Add the ● ingredients, and mix in well with a rubber spatula. (Add 5 g or so of chopped sweet beans or other additions if you prefer.)
Pour the batter into milk carton baking molds (see Recipe ID: 292365) or a poundcake tin lined with parchment paper. Drop the mold or tin lightly on a countertop to even out the batter. (Sprinkle the remaining sweet beans or other additions on top.)
Bake for 35 minutes at 320°F/160°C and it's done. If you are using a milk carton mold, cut the 4 corners with scissors, run a knife along the bottom and remove the cake.
Wrap in plastic wrap to prevent the surface from drying out.
Variation: For a chocolate version, use cocoa powder instead of matcha and dried fruits instead of sweet beans.
Story Behind this Recipe
The beans can be any kind of sweet cooked beans such as amanatto. You don't have to chop them if the beans are small - just use them as is. Amanatto can turn tough if sprinkled on top of the cake. Since this is a cake for dieters, I reduced the sugar and oil as much as possible, but if you want to make it sweeter, add more sweet beans. If the cake is not sweet enough after it's been baked, spread a little brown sugar syrup on top.