Preheat the oven to 350F (180C). Grease and line a 8 inch (20cm) square pan with parchment paper, dividing the pan in half using an aluminum wall. In a medium bowl combine flour with almond flour, baking powder and salt. In a large bowl mix butter with sugar until creamy. Add eggs one at a time, and mix to incorporate. Gradually add flour mixture and milk and mix to combine. Divide batter in half. For the almond batter incorporate almond extract. For the chocolate batter mix cocoa powder, milk and sugar in a small bowl and incorporate in the other half of batter. Pour each batter into one half of the prepared pan. Bake for about 30-35 minutes until a toothpick inserted into the center of the cake comes out clean. Remove from oven, cool for 5 minutes in the pan and then cool completely on a cooling rack. Meanwhile warm the apricot jam, sieve and let cool. When cakes are completely cooled place trim the tops to flatten, and place one on top of the other and trim to equal size. Cut each in half lengthways. Place a strip of chocolate cake on a working surface, brush the top and sides with apricot jam and place an almond cake next to it. Repeat with the other strips of cake on top. Make sure to brush each with apricot jam. Prepare the almond paste. Place the almond flour (ground almonds), powdered sugar and cocoa powder into the bowl of a food processor. Grind to combine. Add apricot jam and almond extract and continue grinding until it comes together. Knead a bit into your hands to come together. Use a rolling pin to roll the almond paste between two sheets of parchment paper, into a thin layer. Cut the almond paste into a 8 x 12 inch (20x30cm) rectangle. Tightly wrap the cake in almond paste (marzipan). Trim the ends and refrigerate until ready to serve.