Add the yeast to a large bowl alongside the sugar and about 3-4 tablespoon of the lukewarm soy milk, gently stir and set aside for about 10 minutes.
In the meantime melt the butter and combine it with the remainder of the soy milk, 3 tablespoon of aquafaba and salt, then pour in the yeast mixture before gradually adding the flour.
Combine the dough with a spatula or wooden spoon and continue to knead the dough by hand on a floured surface once it becomes to dense to mix in the bowl.
After about 5 minutes of kneading, place the dough in a greased bowl, cover with a cloth and leave it to rise in a warm location for about an hour. Within this time the dough should double in size.
Whilst the dough is proving you can prepare the filling: Start by breaking up the marzipan into small chunks and adding it to a bowl. Pour in the aquafaba and lemon juice and use a whisk or fork to blend until the marzipan has broken down and you have a smooth paste.
Toast the almonds in a pan without oil until golden and set aside.
After the hour has elapsed roll out the dough into a rectangular of about 2cm thickness. Spread most of the marzipan mass onto the top, leaving about 3 tablespoon for later. Sprinkle the toasted almonds over the top.
Start on the longer edge of the rectangular and gently roll up the dough, finishing with the edge on the bottom size. Place the roll on a non-stick baking sheet.
Using a knife, cut the roll along the long middle, leaving about 3 cm uncut at the top.
Plait the 2 ends making sure the cut layers remain on the top. Once you get to the end, gently press the dough ends together to finish off the plait.
Place the plait in the oven for about 25 minutes, check on the plait and brush it with the remaining marzipan mixture. Sprinkle more almond flakes across the top (optional) and place it back in the fridge for another 5-10 minutes.
Remove the plait from the oven. In a small har mix the marmalade with a little bit of water and brush it across the plait. Let it cool down almost entirely before attempting to cut the plait.