Step 1

Preheat oven to 180°C/160°C fan-forced. Line 3 baking trays with baking paper.

Step 2

Using an electric mixer, beat butter, sugar, orange rind and vanilla until pale and creamy. Add egg. Beat until combined. Sift flour over butter mixture. Using a wooden spoon, stir to combine.

Step 3

Place dough on a lightly floured surface. Shape into two 25cm logs. Wrap in plastic wrap. Refrigerate for 2 hours or until firm. Remove and discard plastic wrap.

Step 4

Cut into 1cm-thick rounds. Place on trays. Bake for 10 minutes or until golden. Cool on trays for 5 minutes. Transfer to a wire rack to cool completely. Sandwich biscuits with 1 teaspoon passionfruit butter. Serve.