Preheat oven to 350°F or 180°C. Grease a 7 x 11 inches pan (or similar, it can also be a loaf pan).
Add juice from one lemon to a cup of milk, stir and let rest for at least 10 minutes
Meanwhile, in a medium bowl, sift flour and baking powder.
In a large bowl, mix butter with sugar and lemon zest. Then add juice from another lemon and eggs and yolks, one at a time, whisking at high speed for about 10 secs each.
Add 1/3 of the dry ingredients (flour + baking powder) into the mixture and mix. Then add 1/2 of the liquid mixture (milk + lemon juice) and mix. Add again 1/3 of the dry ingredients and mix, add the remaining half of milk and mix, and finally add the remaining 1/3 of flour mixture and mix with folding motions.
Pour batch into the pan and pop in the oven at 350°F (180°C) for 25 to 35 minutes, or until a toothpick comes out clean when inserted. Wait at least 15 minutes for it to cool down before removing from pan, and once removed let it cool (ideally on a cooling rack) for 10 more minutes.
Optional: you can create a delicious crispy coat for the cake with 2/3 cups of caster, granulated sugar and the juice from half a lemon. You mix sugar with juice together and spread all over the cake, it tastes delicious and adds a little crunch when it hardens!