Preheat oven to 180˚C. Line a 9x9 inch square cake pan with grease proof paper.
Place Dr. Oetker Nona Butter Cake Original and eggs in a mixing bowl. Mix at medium speed for 3 minutes.
Add in butter and mix at low speed for 1 minute or until batter is smooth.
Divide the batter into 2 portions, add cocoa powder into one of the bowls and mix well.
Spread a thin layer of original batter on the bottom of the pan and bake for 3 to 5 minutes until set. Top with a layer of cocoa batter and bake for 3 to 5 minutes until set. Repeat the step until all batter are used up. Remove from oven and allow to cool completely before cutting.
Using a ruler, cut the cake into 9 equal parts lengthwise. Using the strawberry jam, attach the pieces to one another in three rows of alternating patterns. Wrap the cake in plastic wrap and chill for at least an hour.
Melt cooking chocolate with “double-boil” and gradually pour in milk and butter, stir until well combined.
Slowly pour the chocolate ganache over the top of the cake. Let the ganache set before cutting