Beat the butter with the sugar and zest until it becomes light in colour. You can use a whisk or an electric mixer.
Add the eggs and beat again until incorporated, very airy and thick.
Add the yogurt and lemon juice and mix. It will look split, it's normal.
Add the flour, salt and baking powder and mix them in using a spatula.
Prepare a 22x11cm / 8x4in pan with baking paper. Cut it to size and stick it in place with a bit of oil.
Place the batter in the pan and level it using a spatula.
For the groove (optional)
Use a butter knife to make a groove along the centre of the batter.
Carefully pour the butter into the groove.
Bake the cake in a preheated oven at 180°C / 350°F for 45min - 1 hour. At the 30min mark check to see if it's golden enough on top. If it is, cover with tin foil or remove the top heat.
For the glaze
Remove the cake from the pan by lifting it from the paper on the sides and place on a cooling rack. Let it cool down completely before adding the glaze or else it will melt and be absorbed by the cake.
Whisk together the lemon juice and sugar and pour it slowly onto the cake. You can use a spatula to move it to where you want it to be. Let the glaze dry for a couple of hours before cutting it (if you can help yourself).
Notes
I added the cup measurement equivalents but always prefer to weigh out your ingredients for a perfect result.