Preheat the oven to 350°F (175°C).

Grease an 8-inch (20 cm) springform pan with vegan butter and line the base with parchment paper.

Gently combine the blackcurrants and powdered sugar in a medium bowl with a spoon or spatula, and set aside while making the cake batter.

Add the butter and sugar to the bowl of a stand mixer fitted with the paddle attachment, and beat on medium-high until pale and fluffy, about 3-4 minutes.

Scrape down the base and sides of the bowl, add the Just Eggs, vanilla extract, and sour cream, and combine.

Sift in the dry ingredients and beat on low speed until a few flour streaks remain.

Add the blackcurrants to the batter using a spatula and gently fold them in.

Pour the batter into the prepared cake pan and sprinkle the top with demerara sugar.

Bake for about 45 minutes until a cake tester inserted into the middle comes out clean. If the cake starts to brown too quickly on top, cover it with aluminum foil and continue to bake.

Cool on a wire rack for ten minutes, then remove from the pan to cool.

Serve warm or at room temperature and drizzle with homemade vanilla sauce.

Combine soy milk, sugar, cornstarch, and turmeric in a medium heavy-bottomed saucepan.

While constantly whisking bring the mixture to a near boil then reduce the heat and continue whisking until the mixture starts to thicken. Cook for another minute or so on low heat, then remove from heat.

Stir in the vanilla extract.

Transfer the sauce to a glass bowl and let cool completely.

Keep in refrigerator until ready to use.