Preheat oven to 180 degree Celsius. Grease 8″ cake tin and line with parchment.
In a medium bowl, whisk flour, baking powder, and salt until well combined. Set aside.
Mix butter and sugar on medium to high speed until pale and fluffy (about 3- 4mins). Reduce speed and add eggs one at a time fully incorporating after each addition. Add vanilla extract.
Stir in flour in small increments, fully incorporating after each addition.
Bake for 35-40mins or until a skewer inserted into the center comes out mostly clean.
Place cakes on wire rack to cool for 10-15mins then turn out onto wire rack.
Butter at room temperature. Stir in with icing sugar. Mix at medium to high spreed until pale and fluffy. Keep going for good 7-8 minutes.