To make the biscuits, beat butter and icing sugar until light and fluffy. Stir in sifted flours and milk and mix well.
Spoon mixture into a piping bag fitted with a fluted tube. Pipe 3 cm wide rosettes, about 3 cm apart, onto greased oven trays.
Cook in a moderate oven, 180c, for 12 minutes or until firm. Cool on trays.
To make passion fruit cream, beat butter in a small bowl with an electric mixer until smooth. Gradually add sifted icing sugar mixture and beat until light and creamy. Beat in pulp to make a spreadable consistency.
Sandwich biscuits together with a heaped teaspoon of passion fruit cream. Dust with extra icing sugar.