Preheat the oven to: electric 180°C / electric (fan) 160°C / gas mark 4.
Grease and line your cake tins.
Put the sugar and grated marzipan into a bowl.
Add the soft butter and mix with an electric hand whisk, or wooden spoon, until you have a smooth paste.
Add the eggs one at a time to combine, each without the mixture curdling. If the mixture does curdle, add a teaspoon of cornflour.
In a bowl, sieve together the cornflour, baking powder and salt.
Add to the egg mixture and fold in gently until all just combined.
Pour the mixture into the two tins, smooth the top gently with a spatula.
Bake for 25-30mins, until a skewer comes out clean and the cake is golden and springy to touch.
Whilst the cakes bake, make the icing by beating together the icing sugar, amaretto/extract and butter together for at least 5mins until light and fluffy.
When the cakes have baked, turn them out onto a wire rack to cool completely.
Once cooled, place a small blob of icing onto your serving plate and put one half of the cake on top, spread the icing over, then the jam (stir the jam to make it easier to spread and stop it from dragging the icing).
Top with the other half of the cake, then dust generously with icing sugar and scatter on some glace cherries.