Preheat the oven to 160°C and grease a 20cm round tin with butter and baking paper.
Beat all cake ingredients in a large bowl until well combined.
Spoon half of the cake mixture into the tin and level the surface.
Roll one-third of the marzipan to fit the tin and place it on the mixture.
Top with the remaining cake mixture and level the surface again.
Bake for 105 to 120 minutes until golden-brown and firm.
Cool the cake for 10 minutes before removing it from the tin.
Brush the cooled cake top with warm apricot jam.
Roll out half the remaining marzipan to fit the top and crimp the edges.
Form 11 balls from the remaining marzipan and attach them to the edge with beaten egg.
Brush the marzipan with egg and glaze under a hot grill for 5 minutes.