1. Preheat oven to 175°C | 350°F.
2. Line a 20cm loaf pan with baking paper.
3. Squeeze the lemons to get 120g of lemon juice for this recipe. You will need about 3 medium size lemons.

For the cake

1. Melt butter in a saucepan or in the microwave. Set aside.
2. In a large bowl, whisk together the powdered sugar, melted butter and lemon zest. Then add fresh lemon juice and stir well.
3. Add the eggs, one at a time, beating after each addition. 
4. Add sifted flour and baking powder, mix until incorporated.
5. Bake in 350°F (175°C) for 40 minutes, until the cake is golden and inserted toothpick comes out clean.
6. Meanwhile, make the syrup. Combine the water and sugar in a saucepan and bring to a boil. Remove from the heat and stir in the lemon juice.
7. Cut the top of the warm cake if you need and invert it onto a rack. Gradually brush the hot syrup over the cake, letting it soak in.
8. Cover in plastic wrap and allow the cake to cool completely, about one hour.

For the glaze

1. in a small bowl, whisk together the sifted powdered sugar and lemon juice. Add more powdered sugar or lemon juice (or water) as necessary to make a thick but pourable glaze.
2. When the cake is cool, carefully transfer it to a wire rack, set this on top of large plate to catch the run-off glaze.
3. Pour the glaze over the top of the cake, then slowly work out to the edges of the cake until the cake is fully covered.
4. Put the chopped pistachio and carefully transfer it to a serving platter. 
5. Let the cake cool at room temperature for about an hour.