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A round Boston Bun, iced and served on a plate, with two slices cut showing sultanas inside.

Thermomix Boston Bun Recipe

Our easy Thermomix Boston Bun recipe is perfect for your next morning or afternoon tea! It's simple to make and freezer friendly too.
Course Desserts, Snacks
Cuisine Australian
Prep Time 30 minutes
Cook Time 40 minutes
Cooling Time 1 hour
Total Time 2 hours 10 minutes
Servings 8 people


  • 20cm Cake Tin


  • 250 grams peeled potatoes chopped into 3cm pieces see notes
  • 220 grams caster sugar
  • 300 grams self raising flour + extra for dusting
  • 1 teaspoon cinnamon
  • 1 teaspoon mixed spice
  • 80 grams sultanas
  • 50 grams raisins
  • 230 grams milk
  • 2 tablespoon desiccated coconut


  • 300 grams soft icing sugar mixture
  • 30 grams butter at room temperature
  • 2 tbsp milk
  • 1 teaspoon vanilla extract
  • ¼ cup desiccated coconut to decorate


  • Line the base and sides of a 20 cm round cake tin with baking paper and lightly grease. Set aside until needed.
  • Add 1000 grams of water to your Thermomix bowl and place the chopped potatoes into the basket. Add the lid and cook for 14 minutes, varoma temperture, speed 2. Check the potatoes with a knife to see if they are cooked through.
  • Pre-heat your oven to 200 degrees.
  • Carefully remove the basket from your Thermomix bowl and drain the water.
  • Place the butterfly attachment in the bowl (carefully as the bowl will still be hot after cooking the potatoes) and return the potatoes to the bowl and add the caster sugar. Mix for 10 seconds, speed 4 to combine. If needed, mix for a further 5 seconds, speed 4 or until smooth.
  • Add the self raising flour, cinnamon, mixed spice, milk and coconut and mix for 10 seconds, speed 4.
  • Add the sultanas and raisins and select the kneading function and mix for 40 seconds.
  • Pour the mixture into your prepared cake tin and gently smooth the surface with a metal spoon/knife.
  • Place the Boston Bun into your pre-heated oven and bake for 35 - 40 minutes or until cooked through when tested with a skewer.
  • Remove the cooked bun from your oven and allow to cool for 15 minutes before carefully removing from the tin and placing onto a wire rack to allow to cool completely.
  • Once the bun has cooled, combine the icing ingredients in a small bowl and mix until smooth. You want your mixture to be stiff enough so that you can spread it onto the bun and it won't run down the sides.
  • Add the icing and sprinkle the coconut over the top.


  • You can use leftover mashed potato if you wish. I would suggest warming it up first to help the sugar dissolve.
  • I used a 20cm cake tin to bake my Boston Bun, you can use a smaller or larger tin if you wish however the cooking time will vary.
  • You can also choose to cook this on a baking tray lined with baking paper if you prefer.
  • I used a combination of sultanas and raisins for this recipe, you can use any type or combination of dried fruit that you wish.
  • This Boston Bun is best stored in an airtight container at room temperature for up to 3 days. It's also freezer friendly either iced or plain.