1. Heat your oven to 150°C. Line the base and sides of a 20cm round deep cake tin with baking parchment, cutting it so that it stands a good 5cm proud of the top of the tin.
2. Roll out one-third of the marzipan to about 5mm thickness and cut a circle that will just fit inside the cake tin. Set aside.
3. Using an electric hand-held whisk or mixer, beat the butter, sugar, eggs, flour, cinnamon, orange zest and lemon zest together in a large bowl until thoroughly blended. Stir in the sultanas, currants and glace cherries until thoroughly combined.
4. Put half of the mixture into the prepared tin and level the surface. Lay the prepared marzipan circle over the mixture, then spoon the rest of the cake mixture on top and smooth the surface.
5. Bake for about 2½ hours until the cake is well risen and firm to the touch. Leave to cool in the tin for 10 minutes before turning out onto a wire rack to cool completely.
6. When the cake is cooled, warm the apricot jam gently with a splash of water in a small pan over a low heat, sieve, then brush over the top of the cake. Roll out half of the remaining marzipan and cut to fit the top. Press firmly on the top and crimp the edges decoratively. Mark a criss-cross pattern on the marzipan with a sharp knife, if you like.
7. Form the remaining marzipan into 11 balls. Brush the marzipan on the cake with beaten egg, then place the marzipan balls evenly around the edge. Brush the balls with beaten egg too. Use a cook’s blowtorch to brown the marzipan balls. Alternatively, do this by putting the cake under a hot grill for a few moments; watch it carefully because marzipan burns easily.