In a bowl, mix the flour with the baking powder, sodium bicarbonate and salt. Add the sugar and all the other ingredients up to and including the oat milk, mix quickly to form a smooth batter. Transfer half of the batter to the prepared mould.
Thoroughly combine the oat milk and cocoa powder, mix into the second half of the batter, transfer to the mould. Using a fork, stir in a spiral motion and create a marble effect through both batter mixtures.
Approx. 50 mins. in the lower half of an oven preheated to 180°C. Insert a wooden skewer to check whether the cake is cooked through. Remove from the oven, allow to cool slightly, tip onto a cooling rack and leave to cool completely.
Sugar-roasted almonds & glaze
Bring the water, vanilla sugar, gingerbread spice and sugar to the boil in a cast iron or stainless steel pan. Add the almonds, reduce the liquid over a medium heat, stirring constantly until the sugar is dry. Continue to stir until the sugar begins to melt again and forms a glossy coating over the almonds. Immediately spread the mixture onto a baking tray, leave to cool. To make the glaze, melt the chocolate and margarine in a bain-marie. Spread the glaze over the cake, top with the sugar-roasted almonds, leave to dry.