Heat the kabocha (I use a microwave), mash it, and chill it in the refrigerator. Strain it if you want it to look prettier.
Heat the egg in a hot water bath and add the sugar in 2~3 batches while mixing. (When the egg has warmed to about body temperature, remove from the heat.)
Whip the mixture until it's stiff enough to create ribbons like in the picture.
Sift together the "A" ingredients and fold into the mixture from Step 3 in 2~3 batches.
When everything is mixed in, the batter should be smooth.
Take some of the batter from Step 5 and mix it in with the kabocha from Step 1. (This will make it easier to mix the kabocha in with the batter.)
Add the kabocha mixture into the batter from Step 5 and mix until smooth.
Add the warmed (50℃) butter to the batter and mix together.
Add the kuro-mame and the rum and gently mix. The batter is ready.
Pour the batter into the pan and put it into an oven preheated to 170℃. Bake for about 45 minutes.
Once baked, drop the pan lightly to release the steam. Remove the cake from the pan and let cool.
All done. The color of the pumpkin gives it a pretty finish. The subtle sweetness of the kuro-mame accentuates the flavor.
Story Behind this Recipe
A simple cake to make when kabocha is in season. It's so light and easy to eat.
Adjust the amount of sugar depending on the sweetness of the kabocha squash and cooked beans. (I use home-cooked beans, which are not so sweet.) If you put the cake in a vinyl bag after baking, it will become even more moist.