Nutrition: per serving (8)
Heat the oven to 180C/160C fan/gas 4. Butter and line a 20cm square cake tin with baking paper. Put the butter, sugar and orange zest in a large bowl, and beat using an electric whisk for 5-6 mins or until very light and fluffy.
Drop in the eggs a tablespoon at a time, whisking until combined before adding the next tablespoon. Fold in the yogurt and pistachios, then sift over the flour, baking powder and a small pinch of salt. Fold gently to combine, then pour into the lined baking tin.
Smooth over the top, then bake for 25-30 mins or until a skewer comes out clean. Leave to cool for 10 mins in the tin while you make the syrup.
Put the sugar and orange juice in a small pan. Bring to the boil, then reduce to a simmer and bubble for 2-3 mins before removing from the heat.
Poke holes into the cake with a skewer, then pour over the syrup. Leave to soak for 10 mins, then transfer to a wire rack. Brush with any remaining syrup.
Once completely cool, sprinkle with chopped pistachios to decorate.
