Start by creating the chocolate filling ahead of time: Melt the chocolate spread until super runny, then mix with the plant milk. Transfer the ganache to an ice cube tray and freeze for 2 hours or until set.
Preheat your oven to 180°C and lightly grease 4 pudding molds. Dust the inside of each mold with a thin layer of cacao powder.
Sift the flour, cacao powder, baking soda and salt into a large bowl and mix in the brown sugar. In a separate jug, combine the milk, warm water, apple cider vinegar, flaxseeds, sunflower oil and cinnamon.
Mix the dry and wet ingredients with a whisk, then pour 2 tablespoons of the mix into each pudding mold. Remove the chocolate cubes from the freezer and place 1 cube into the center of each mold. Fill halfway with the remaining batter.
Gently tap the mold on a work surface to remove any air bubbles, then bake in the middle of the oven for 13 minutes - do not open the oven door in the process, in order to maintain the heat.
Remove the pudding mold from the oven immediately and gently loosen the puddings with a knife. Flip them onto your serving plates and serve immediately.