Beat the butter with the sugar until it becomes light in colour. You can use a whisk or an electric mixer.
Add the eggs and beat again. Beat until they are fully incorporated but also very airy and thick.
Add the yogurt and vanilla extract and mix. It will look curdled, it's normal.
Add the flour, salt and baking powder (dry ingredients) 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)
Cut the butter into thin strips.
Place the butter along the centre forming a line and press down gently.
Bake the cake in a preheated oven at 180°C / 350°F for 1h15min or until a skewer comes out clean from the centre. At the 30min-45min mark check to see if it's golden enough on top. If it is, cover with tin foil or remove the top heat.
When you poke it to see if it's ready, go beyond the center of the cake to the base where it takes longer to bake. Wait 3 seconds before pulling off the skewer and check that no raw crumbs are stuck.
Once the cake is ready, remove it from the oven and place it on a wire rack to cool down. Once cool, remove it from the pan lifting it from the paper and dust with icing sugar.
Notes
I added the cup measurement equivalents but always prefer to weigh out your ingredients for a perfect result.