Pre-heat your oven to 200C/180C Fan/Gas Mark 6. Line an 8" Square Pan with greaseproof paper.
In a small bowl, break up the dark chocolate and melt in the microwave in 20 second intervals, stirring in between to make sure it doesn't burn.
In a large mixing bowl, whisk together melted butter vegan and both sugars. With an electric/stand mixer, go for a solid 3-5minutes so it is totally combined. Add in the apple sauce and vanilla and mix again.
Now, add the chocolate slowly and combine once again.
Add the flour and cocoa powder, fold gently into the wet mixture with a rubber spatula or wooden spoon until just combined. Fold in the chopped chocolate. Pour the batter into the lined pan.
Bake for 30 minutes, until no longer wobbly in the middle! Let cool on a wire rack before slicing. Optional: melt about 25g dark vegan chocolate and drizzle over to make them look extra cute!