1. Warm your oven to 180°C/Fan 160°C/Gas 4. Grease a 20cm x 26cm baking tin with sunflower spread and line it with baking paper.
2. Spoon the ground flaxseeds into a small bowl and add the oat milk and 1 tbsp vanilla extract. Stir well to combine and set aside. Finely chop the dates. Pop them in a separate small, heatproof bowl. Pour over the hot espresso and stir well to combine. Set aside to soak for at least 10 mins.
3. Fill a pan with water till it's about one-third full. Pop it on the hob and bring to a simmer. Break the vegan chocolate into small chunks and add it to a heatproof bowl (one large enough to sit on top of the pan). Add the sunflower vegetable spread to the chocolate, along with the golden syrup.
4. Put the heatproof bowl over the simmering water, making sure that the bottom of the bowl is not touching the water. Turn the heat down to very low. Melt the chocolate, spread and syrup together, stirring frequently, till smooth and fully combined. Remove the bowl from the heat and set aside to cool a little.
5. Tip the flour into a large, clean bowl and add the ground almonds, 1 tsp baking powder and ½ tsp bicarbonate of soda. Whisk to mix the dry ingredients together. Set aside.
6. Add the caster sugar and Demerara sugar to the melted chocolate with a good pinch of salt. Beat to combine.
7. Scoop in the soaked flaxseeds and the dates, with any liquid from their bowls, and stir well to mix. Finally, fold in the dry ingredients till just combined.
8. Scoop the batter into the baking tin and smooth out with a spoon. Bake for 25-35 mins, till set on top with a slight wobble in the middle. Set aside to cool in the tin.
9. Once cooled, turn the brownies out of the tin, slice into 9-12 pieces. The brownies will keep in an airtight tin for around a week or can be frozen for up to 3 months.