Ingredients:

•   250 g    Unsalted Butter, softened
•   250 g    Sugar
•       9 g    Vanilla Sugar
•          4    Eggs
• 1 pinch    Salt
•   300 g    Flour
•       7 g    Baking Powder
•   150 g    Cream Cheese, softened
•    4 tbs    Lemon Juice
•    2 tbs    Cocoa Powder

Directions:

Cream butter, sugar and vanilla sugar in a bowl with hand mixer, then add eggs and salt until well blended.
Mix flour with baking powder and carefully mix into the butter/sugar mixture.
Blend Cream cheese and lemon juice and fold into dough.
Cover a jelly roll pan (15×10 inches/38×26 cm) with parchment paper.Use up half the dough and place dollops on parchment paper (see picture below).
Blend the cocoa into the remaining dough and spoon into the free spots of the paper.
Smooth out top with a dough scrapper.
Bake in preheated convection oven for 25 – 30 minutes at 325ºF.
Let the cake cool, sprinkle with confectioners sugar or brush with a lemon glaze (lemon juice and confectioners sugar).