I make an almond cake which has a layer of marzipan, if that would serve your purpose. The top is plain, but could be decorated I guess. It is delicious, best made a day or two in advance and keeps really well, a couple of weeks if it doesn't get eaten up!
Sticky Almond Cake
225g/8oz butter
225g/8oz caster sugar
50g/2oz plain flour
175g/6oz ground almonds
1/2 tsp almond essence
350g/12oz white marzipan
4 eggs
icing sugar for dusting
1.Grease and base-line a 8½ - 9” spring-release cake tin
2.Cream butter and sugar until very pale
3.Gradually beat in eggs, adding a little flour if mixture curdles
4.Stir in remaining flour
5.Gently fold in ground almonds and essence
6.Roll out marzipan slightly larger than cake tin and using tin as template cut marzipan into a circle
7.Place half the cake mixture in the cake tin, top with the marzipan, then finish with the cake mixture
8.Bake at 180°C, 350°F, gas 4, for about 1¼ hours or until firm to the touch, covering lightly with foil if necessary
9.Cool for 5 mins in tin then remove from the tin and cool on a rack
10.Wrap in foil and store for at least 1 day before serving.
11.Dust with icing sugar
I don't worry about it being white marzipan, just use whatever has highest almond content. It is delicious, a favourite 'special' cake.