Preheat the oven to 180°C and line a 20cm deep cake tin with baking parchment.
Beat butter, sugar, flour, almonds, eggs, and lemon zest in a mixer for one minute.
Spoon batter into the tin and level with a palette knife.
Bake for 45 minutes, cover with foil, and bake for 15 more minutes until clean.
Cool the cake completely in the tin on a wire rack.
Heat cream in a pan until almost boiling, then stir in chocolate until melted.
Pour the cool ganache over the cake in the tin and let set.
Colour 175g of marzipan green and cut out 20 holly leaves.
Colour remaining marzipan red and roll into 30 small berry balls.
Remove cake from tin, peel off parchment, and decorate with marzipan wreath.