Break almond paste into a large bowl and beat in butter, sugar, eggs and almond extract until light and fluffy. Beat in the flour and salt. Split batter into three equal portions, mixing one portion with green food colouring, one with yellow and one with red. Spread each portion out to 5mm thickness into the bottom of an ungreased 20x30cm baking tin.
Bake each layer for 12 to 15 minutes in the preheated oven, until lightly browned. Allow to cool.
On a chopping board, stack the cake, spreading tops of the first two layers with raspberry jam. Spread melted chocolate over top of the third layer. Chill in the refrigerator 1 hour or until jam and chocolate are firm. Slice into small rectangles to serve.