Preheat oven to180°. Grease and line 2 round cake tin.

Beat egg whites until soft peaks form.

Sift flour baking powder, beat butter and sugar until smooth and fluffy.

Add yolks in the butter mixture and stir in sifted flour. Finally add egg white peaks carfully fold in flour mixture. 

Transfer the mixture to two prepared pan, bake the cakes for approx 45 minutes.

Marshmallow fondant:-Place the marshmallows in a large microwave safe bowl and microwave on high for 30 seconds to 1 minute to start melting the marshmallows. Carefully stir the water until mixture is smooth. Add confectionr's sugar and knead the dough to make it very soft. Rub your hands throughly with butter before beginning the kneading and the sticky dough will become workable and pilable. Turn the dough out  to a working surface dusted with icing sugar and continue kneading until the fon...

Now allow the fondant to come to the room temperature. Roll it out on to a flat surface dusted with icing sugar. Cover the cake with this rolled fondant.  Make different shapes (flowers, leaves, stars, etc.) as you may like and place on the cake surface and sides.