Castella - カステラ
One of my favorite cake in Japan is the "Castella". It's a Portuguese cake imported in Japan in the XVIe. Now it's like a traditional japanese cake you can find everywhere. Castella is sold at many old established Japanese sweets stores, departement stores and even supermakets.
It's a sponge cake and so good that you can eat the whole one for breakfast.
The basic one is made of just 4 basic ingredients: eggs, bread flour, sugar and honey. But you can find the matcha castella, so delicious.