Boil and mash the red beans.
Melt dark chocolate and butter using a double boiler.
Add the mashed red beans, sugar, and eggs to the melted mixture and mix well.
Sift cake flour, cocoa powder, and salt into the mixture.
Combine all ingredients thoroughly.
Pour the batter into a heat-resistant container.
Bake in a preheated oven at 180°C for 25-30 minutes.
Cool and cut into serving sizes.