Preheat oven to 350°F.

Spray a 9x9” square baking pan with nonstick spray

In a bowl, mix the salt, baking powder, 1 cup sugar and flour together with a fork

In another bowl place the egg yolks and using a mixer, whip for 5-7 minutes until the yolks become thick and pale

Slowly add the flour mixture alternating with the butter and lemon juice. Finally mix in the lemon zest

In another bowl, beat the egg whites until stiff 

Carefully fold in the egg whites into the cake mixture in 2 – 3 installments using a spatula. Use round movements to avoid deflating the egg whites

Pour the batter into the prepared pan and bake until golden brown, about 20-30 minutes

Remove from the oven and place on baking rack for 20 minutes

Invert the pan into the baking rack and unmold 

Cool cake completely

Wrap the cooled cake in plastic and freeze for a couple of hours for easy cutting and stuffing

Mix all the ingredients together until creamy

Spoon the crème into a piping bag and snip the bottom 

Remove the cake from the freezer and cut into small snack cakes 

With a knife, make deep 3 incisions over the surface of the cakes making sure you leave a large pocket for the crème

Insert the piping bag into each pocket and squeeze to stuff the pastries

Clean the tops of the cake and refrigerate while you make the frosting

Place butter, lemon juice and sugar into a bowl

Mix on medium speed until nice and creamy

Place the frosting into a piping bag fitted with a large Icing tip 

Slowly Pipe the frosting over surface 

Enjoy!