Preheat the oven to 180°C and grease a 23cm springform cake tin.
Melt butter in a saucepan then whisk in sugar, eggs, and orange oil until smooth.
Sift flour, bicarbonate of soda, and spices into a bowl and stir in salt.
Fold the butter mixture into the dry ingredients followed by carrots, sultanas, pecans, zest, and juice.
Bake the mixture for 1 hour or until a skewer comes out clean.
Cool the cake in the tin briefly before moving to a wire rack.
Reduce orange juice and sugar in a saucepan to create a sticky glaze.
Brush the glaze over the warm cake and let it cool completely.
Beat butter and icing sugar until combined, then add vanilla and orange oil.
Fold in cream cheese gradually until light and fluffy.
Color small portions of icing with orange and green food coloring for decoration.
Slice cake horizontally and fill with one third of the plain icing.
Frost the top and sides of the cake and allow to crust.
Pipe carrot shapes and stars onto the cake and decorate sides with pecan halves.