Step 1
Preheat oven to 350 degrees F (175 degrees C). Grease and flour two 9-inch square cake pans.
Step 2
Sift 2 1/3 cups plus 1 1/2 tablespoon flour 1/2 cup plus 3 tablespoons cocoa powder baking powder and salt together in a large bowl.
Step 3
Beat butter and white sugar together in a bowl with an electric mixer until light and fluffy about 4 minutes. Add eggs one at a time beating well after each addition. Beat in vanilla extract. Add flour mixture alternately with 1 cup plus 1 1/2 tablespoon milk mixing batter gently between each addition.
Step 4
Divide batter evenly between the prepared cake pans.
Step 5
Bake in the preheated oven until a toothpick inserted into the center comes out clean 30 to 40 minutes. Cool for 10 minutes in the pan. Invert onto a wire rack to cool completely about 30 minutes.
Step 6
Trim tops of cake layers to make sure they are flat. Set 1 layer on a serving platter. Spread jam on top; cover with second layer. Spread chocolate buttercream frosting over top and sides of the cake reserving about 2 tablespoons frosting.
Step 7
Pinch off a piece of marzipan the size of a golf ball. Add red food coloring and knead until color is evenly distributed.
Step 8
Dust a flat work surface with confectioners' sugar and roll out remaining undyed marzipan. Cut out a 9-inch square; carefully transfer to the top of the cake.
Step 9
Roll trimmings of marzipan and cut into four 9x1-1/2-inch strips. Cut 3 rectangular notches into 1 edge of each strip. Press strips onto the sides of the cake notches facing down; gently press top and strips of marzipan together to adhere.
Step 9
Roll out red marzipan and cut into squares of varying sizes. Spread a little of the reserved frosting on the back of each square to act as a glue; arrange in a random Minecraft pattern on top of the cake.