Preheat oven to 350F and grease or line an 8" square pan with parchment paper.
Sift flour and salt in a separate bowl and set aside.
Chop the chocolate and melt it in the microwave. Set aside.
In a bowl of a standing mixer, whip butter and sugar until lighter in color and fluffy.
Stir in egg yolks following the melted chocolate.
In a separate bowl, whip the egg white to a medium peak about 1 and a half minutes.
Fold in egg whites.
Fold in the flour mix.
Bake for 20-25 minutes until a toothpick comes out dry from the center of the cake.
Allow the cake to cool completely. Gently remove the cake from the pan dust it with the Matcha Powder and slice to 16 pieces.