Makes 850g (about 4 cups) of buttercream. Enough to generously frost about 16-20 cupcakes, or a 20-cm/7.5-inch three-layer cake. Active time: 30 minutes*.
Ingredients
For the spicy pumpkin puree:
240g (or 1 cup) homemade or store bought pumpkin puree
225g (or 1 cup) unsalted butter, cubed and softened at room temperature
Instructions
Start with the spicy pumpkin puree:
Combine all the ingredients for the spicy pumpkin puree in a small saucepan and heat over low heat, stirring continuously with a wooden spoon, until the butter has melted and the sugar has dissolved. Crank up the heat to medium and continue to heat the mixture, stirring constantly, until the mixture comes to a boil. As the mixture is quite thick, you need to look for slow bubbles.
Once the puree is bubbling, set the heat to medium-low and cook the mixture for 5 minutes, stirring slowly but continuously, to allow some of the moisture to evaporate. Then remove the puree from the heat and blitz to a finer puree in a blender or with a stick blender.
Allow the spicy pumpkin puree to cool to room temperature, then chill for about 30 minutes to an hour in the fridge.
While the pumpkin puree is chilling, prepare the buttercream:
Combine sugar and water in a medium-sized saucepan. Heat over low heat, stirring with a metal spoon until the sugar has dissolved and the syrup is clear. Crank up the heat to medium-high and allow syrup to come to a boil.
In the meantime, place the egg whites in a medium-sized, heatproof bowl and mix (with a mixer fitted with the whisk attachment) until the whites are almost able to hold soft peaks.
Once the sugar syrup has come to a boil, clip on a candy (or sugar) thermometer or insert the probe of a multimeter. Cook until the syrup reaches a temperature of 113°C/235°F, then immediately remove from the heat and slowly drizzle the hot syrup into the bowl with the egg whites, mixing continuously to prevent the eggs from scrambling. Don't pour the syrup onto the whisk, or the syrup may splatter against the sides of the bowl (or into your face!). Instead, aim for a spot close to the whisk.
Once all the syrup has been added, keep mixing until the bottom of the bowl feels cool to the touch and the meringue has cooled down to at least body temperature.
Once the meringue has cooled to room temperature, start adding the butter to the meringue one cube at a time, mixing well after each addition. As you're adding the butter, the mixture will lose most of its volume and at some point may even start to look as if it's separating. Don't panic! Just keep mixing and the buttercream will magically come together and become smooth and creamy.
Add the chilled pumpkin puree to the buttercream one tablespoon at a time, mixing well after each addition. Once you’ve added all the puree, mix for another 2 minutes, or until the buttercream looks creamy and smooth.
Use immediately or store in an airtight container or a zipper bag in the fridge for up to a week. To use buttercream that has been refrigerated, first allow to come to room temperature then beat with the mixer until smooth and spreadable again.
Cakes or cupcakes decorated with buttercream generally keep 3-5 days, stored in an airtight container in the fridge. Allow cakes and cupcakes decorated with buttercream to come to room temperature before serving, because this improves the texture of the buttercream. For a big cake, this may take up to 4 hours
Notes
* Bear in mind that the pumpkin puree needs time to cool! You can make the pumpkin puree the day before you intent to make the buttercream. That way, the puree has time to thoroughly chill in the fridge overnight.
Recipe by The Tough Cookie at https://thetoughcookie.com/2015/11/10/how-to-make-italian-pumpkin-buttercream/