Jose Agar
Baking

Yo-Yo Biscuits: Custard Powder Shortbread with Passionfruit Cream

A soft, pale biscuit that melts on the tongue, joined in matched pairs with a tangy passionfruit buttercream. The custard powder is what sets it apart.

The Jose Agar Editorial Team Tested and written in a home kitchen · Updated July 2026

How this was made: Recipes are developed and kitchen-tested by our editorial team. We use AI tools to assist with drafting, structuring and proof-reading; a human editor reviews and tests every recipe before publication. No fictional author is used.

Pale yo-yo biscuits sandwiched with passionfruit buttercream, stacked on a plate
Yo-yos: ridged custard powder biscuits joined in matched pairs with a soft passionfruit filling.
20 minPrep
15 minCook
about 16Makes
EasySkill

Yo-yos take their name from the childrens toy: two round, ridged halves pressed together with a soft filling in the middle. They are a fixture of the New Zealand biscuit tin, close cousins to melting moments, and just as at home on a morning tea table or packed into a school lunchbox. What makes them worth learning is the crumb, which is short and pale and dissolves rather than snaps.

The one ingredient that defines a yo-yo is custard powder. Where a melting moment leans on cornflour for tenderness, the custard powder does the same softening job but also lends a pale golden colour and a faint vanilla-custard flavour that reads as gently old-fashioned. If you have made our melting moments, the method here will feel familiar; the swap of custard powder for cornflour is the whole difference.

Ingredients

Biscuits

  • 200 g butter, softened
  • 1/2 cup icing sugar, sifted
  • 1 tsp vanilla extract
  • 1 1/2 cups plain flour
  • 1/2 cup custard powder

Passionfruit buttercream

  • 75 g butter, softened
  • 1 cup icing sugar, sifted
  • 2 tbsp passionfruit pulp (about 2 passionfruit)
  • 1 tsp milk, only if needed to loosen

Method

  1. Heat the oven and line the trays. Set the oven to 180°C (fan 160°C). Line two baking trays with baking paper.
  2. Cream the butter and sugar. Beat the softened butter, sifted icing sugar and vanilla until pale and fluffy. Taking this stage properly is what gives a soft, short crumb.
  3. Add the dry ingredients. Sift in the plain flour and custard powder and stir until the mixture comes together into a soft dough. Stop as soon as it holds; overworking toughens the biscuit.
  4. Roll and flatten. Roll heaped teaspoons of dough into balls a little smaller than a walnut. Space them well apart on the trays, then press each one with a floured fork to flatten slightly and leave the ridged top.
  5. Bake until just pale golden. Bake for 12 to 15 minutes, until set and firm to a light touch but only just coloured at the edges. They should stay pale; a deep brown means a crisper, less tender biscuit.
  6. Cool completely. Leave the biscuits on the tray for five minutes to firm up, then move them to a rack. They are fragile while warm, so do not rush this.
  7. Make the passionfruit cream. Beat the butter, sifted icing sugar and passionfruit pulp until smooth and pale. Add the milk only if the filling is too stiff to spread.
  8. Sandwich in pairs. Sort the cooled biscuits into matched pairs by size. Spread a teaspoon of buttercream on the flat underside of one and press its partner gently on top.
Tips
  • Custard powder is the point of a yo-yo. Swap it for cornflour and you have made a melting moment instead; both are correct, they are simply different biscuits.
  • Use icing sugar rather than caster in both the dough and the filling. It dissolves smoothly and keeps the melt-in-the-mouth texture.
  • Dip the fork in flour between presses so it lifts away cleanly and leaves a neat ridged pattern rather than dragging the dough.
  • No passionfruit in season? Lemon juice and a little zest, or plain vanilla, make good fillings on the same buttercream base.
  • Store unfilled biscuits airtight for up to a week, or freeze filled or unfilled yo-yos for up to three months. Once sandwiched, they are best eaten within two to three days as the filling softens the biscuit.

For another buttery bake to keep in the tin alongside these, our ginger crunch slice works on the same love of a short, rich base. To read more about how we test and write these recipes, see our editorial and AI policy, or browse the full collection on the home page.

Sources & references

Background reading used while developing and verifying this recipe. Quantities and timings were confirmed by our own kitchen testing.

  1. Chelsea Sugar, Yo yo biscuits, for the traditional New Zealand proportions and custard powder base.
  2. VJ Cooks, Passionfruit yoyos, for guidance on the passionfruit buttercream filling.
  3. Cooking with Nana Ling, Yoyo biscuits, for background on shaping and storage.
  4. New Zealand food-safety guidance on home storage of butter-based biscuits at room temperature and in the freezer.

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