Heat oven to 160°C fan bake. Grease and line a 17cm x 27cm slice tin with baking paper with an overhang on all sides.
Place the eggs and sugar in a bowl and beat until pale and creamy then beat in the oil. Stir in the grated carrot, walnuts and sultanas.
Sift the flour, salt, cinnamon, baking powder and soda over the carrot mixture then stir to combine. Spread the mixture into the prepared tin and bake for 50 minutes or until a skewer inserted in the center comes out clean. Remove to cool completely.
To make topping, beat cream cheese until smooth then beat in icing sugar, lemon zest and juice. Spread over cooled cake and cut into squares.