Heat oven to 180C/fan 160C/gas 4. Butter eight 150ml ramekins and line the bottoms with circles of non-stick baking paper. Divide the cake mix between the ramekins, transfer to a baking sheet and slide into the oven. Bake for 30 mins until springy and dark golden brown. Leave until cool enough to handle, then run a round-edged knife around the edge of the each cake. Turn out and cool completely on a rack.
If the cakes have risen into peaks, make flat by slicing the tops off with a serrated knife. Melt the jam with 1 tbsp water and brush over the top of the cakes. Lightly knead the marzipan and shape eight golf ball-sized balls. (You will have some left over – wrap up well for another time.) Using a rolling pin, gently roll the balls into flat circles, approx 1cm thick and the same diameter as the cakes. Sit the marzipan on the jammy side of the cakes. Do the same with the icing, brushing the marzipan with a little cooled, boiled water to help it stick.
Beat the egg white until just frothy and broken up. Spread the caster sugar over a plate. Dip the cranberries and rosemary in the egg white, shake off the excess and roll in the caster sugar to create a frosty effect. Leave to dry for 15 mins. Tip away all but 2 tsp of the egg white and mix with the icing sugar to create a thick paste. Use to fix two cranberries and a sprig of rosemary to the top of each cake. Decorate with gold ribbon. The cakes will keep in an airtight container for up to a week.