Place the butter and sugar in the bowl of your stand mixer and whisk until light and fluffy. Add the eggs one by one. Let it whisk through. Add the vanilla essence and the orange juice.
Mix the flours with the baking powder, salt and ginger powder.
Add the flour mix to the egg mixture and whisk until just combined.
Cut the rhubarb in small slices and add this to the batter together with the chopped pistachio. Add the orange zest and spoon everything through.
Cover a baking tin with baking paper or grease the sides. Pour the batter into the baking tin. Sprinkle the almond slivers over the top.
Bake the cake in the preheated oven for about 1 hour and 25 minutes but check half way if it is not going to fast. When the cake becomes too dark cover with aluminium foil and leave to cook for a bit longer.
Remove from the oven and check with a wooden skewer if the cake is cooked in the middle. Leave to cool completely before cutting.