To make the shortbread: Beat butter and sugar until light and fluffy. Add flour and ground almonds to form a soft dough. Press dough into a greased and lined 20x20cm tin. Bake at 180 C / Gas 4 for 20 to 25 minutes or until pale golden brown. Let cool in the tin.
To make the caramel filling: Heat butter, sugar, syrup and condensed milk over low heat. Bring to the boil, stirring constantly for 5 to 7 minutes or until the mixture thickens and is a pale caramel colour.
Spread caramel on cooled shortbread and let set for about 40 minutes. Melt chocolate over low heat. Spread melted chocolate on top of caramel and sprinkle with toasted almonds.