Preheat oven to 160C. Using an electric mixer, beat butter and sugar until pale and fluffy. Add eggs, one at a time, beating well to combine, then add lemon rind, saffron and milk and beat to combine. Add yoghurt, pistachios, flour and baking powder and fold to combine. Spoon into a buttered and base-lined 28cm fluted tart pan and bake for 25-30 minutes or until golden and centre springs back when lightly pressed. Cool in pan for 10 minutes, then remove from pan and cool on a wire rack placed over a tray.
Meanwhile for yoghurt glaze, combine yoghurt and lemon juice in a small bowl and mix until smooth, sieve over icing sugar and mix to combine, adding a little water if necessary to reach a drizzling consistency. Pour over cake while still warm, allowing to drip over sides. Scatter with pistachio slivers and serve warm or at room temperature.