Seperate egg white and yolk in a mixer mix d egg white untill stiff peak

In another bowl whisk d yolk add d salted butter and sugar mix very well add ur vannilla flavour and mix continuesly

Now you can add your flour and bakinh powder and continue mixing it will be a little hard gradually pour ur egg white and mix

Greese ur pan and pour d mixture heat ur oven at 150 degrees and bake for 30mints and ur soft flyffy sponge cake is ready