Mix all ingredients together except vegetable oil and chocolate paste with mixer on low speed for 2 minutes and medium speed for 4 minutes until fluffy.
Add the vegetable oil to the batter and mix on low speed until well combined.
Divide into two doughs, one dough with chocolate paste
Pour the batter into a 20x7 cm diameter pan alternately, white and brown.
Bake in an oven with an upper temperature of 160°C and a lower temperature of 140°C for 60-70 minutes.
Brush the top of the Castella with Carat Supercrem Crunchie.
