Finnish word soijakakku comes from Finnish kakku, Finnish soija (Soy.)

Detailed word origin of soijakakku

Dictionary entry	Language	Definition
kakku	Finnish (fin)	(slang) bit (prison sentence). Cake. Pie (whole of wealth or resource).
soija	Finnish (fin)	Soy.
soijakakku	Finnish (fin)	Soy cake (cake made of soy flour). Soybean meal (residue from extraction of soybean oil from soybeans, used chiefly as animal fodder but also as raw material for various soy products for human use).