Wrap the tofu with a kitchen towel to remove moisture.
Blend the tofu, plain yogurt, and sweetener ingredients in a blender until smooth.
Prepare espresso or strong coffee.
Soak castella (sponge cake) or oatmeal in coffee.
Layer the coffee-soaked castella in a cup, then add the tofu yogurt cream on top.
Finish by dusting cocoa powder with a sieve.
Refrigerate for about 1 hour and enjoy chilled.