In a large bowl, whisk together the flour, mustard powder, baking powder and salt.
Rub in the cold cubed butter with your fingertips until you have a mixture that looks like rough breadcrumbs
Stir though the watercress
Make a well in the centre and pour in the yoghurt and add the marmite. using a blunt round ended knife or a metal spoon, stir the mixture together until you have a nice soft and craggy dough that isn't too wet. If your dough is a little dry add a splash of dairy-free milk, if too wet add a sprinkle of flour.
Very gently knead the dough so it looks a bit smoother and then pat out with your fingers until it's about 3cm deep. Using a 5 or 6 cm ring cookie cutter, firmly stamp out circles and then place upside down on the lined baking sheet.
Pull the leftover bits together and briefly knead again then repeat the process - these scones will be less perfect but still taste fantastic
Leave the scones, lightly covered, to rest for 20-30 minutes
Preheat the oven to 220℃ or 200℃ Fan
Mix together 1 tbsp dairy-free milk with 1/2 tsp marmite and brush the tops of the scones, being careful it doesn't dribble down the sides
Bake for 12 minutes until beautifully risen and golden. Cool on a wire rack.
