Whisk together the butter and oil until smooth. Then add the salt, baking powder and sugar. Add the rest of the ingredients, finishing with the flour.
Trace the shape of your mould on baking paper using a pencil (see video for more reference) and cut it out. Fold the shape of the mould, keeping the pencil facing the outside os it doesn't have contact with your dough. Use about a tsp of vegetable oil to stick it to the inside of the mould, with the pencil facing the outside.
Add 1/3 of the dough and level. Sprinkle half the cinnamon sugar on top. Repeat with another layer and finish with the last 1/3 of dough.
Use a skewer or knife to go back and forth to marble the cinnamon sugar. You can see more details of how to do it on the video.
Take to the oven at 180C for 40-45min or until you put a skewer or knife in and it comes out clean.
Let cool completely and remove using the sides of the baking paper.