500g(4cups)powdered sugaror icing sugar or icing mixture
½cup(½cup)waterhot from the kettle
2teaspoon(2teaspoon)vanillamore or less to taste
180g(1cup)chocolatedark, milk or white
INSTRUCTIONS
In a heatproof bowl or jug, whisk together the powdered sugar, hot water, and vanilla until smooth.
Strain the mixture through a fine sieve into a clean bowl or jug (optional but recommended, this catches any undissolved sugar lumps for an even smoother result). Let stand for at least 10 minutes to allow the sugar crystals to fully hydrate and dissolve. A crust may form on top, give it a good stir to break it down before using.
In a stand mixer fitted with the paddle attachment, beat the butter on medium-high for 10-15 minutes, until pale and fluffy. The extra few minutes past 10 make a noticeable difference in lightening the color. A hand mixer can also be used.
While the butter is mixing, melt the chocolate in the microwave in 30-second increments, stirring between each, don't go too aggressively or it will burn. Set aside to cool to room temperature, this gives it time to cool while you continue with the recipe.
Give the sugar mixture a final stir to break down any crust that has formed.
With the mixer running on low, slowly stream in half the sugar mixture. Mix for 1 minute to combine, it will look curdled at this stage, this is normal.
Slowly stream in the remaining sugar mixture and mix until combined.
Continue beating on medium for 15 minutes or longer. The longer you mix, the silkier the result, and it gives the sugar another chance to fully dissolve.
Add the cooled, melted chocolate to the buttercream and mix for a further 5 minutes, until fully incorporated and smooth. Make sure the chocolate has cooled to at least room temperature before adding, hot chocolate will melt the butter and split the buttercream.
NOTES
This is a half batch of my hot water buttercream pillar recipe with melted chocolate added, a good example of how the base method scales.
The extra hot water compensates for the melted chocolate firming the buttercream once chilled.
Always let the chocolate cool to room temperature before adding, hot chocolate will melt the butter and split the buttercream.
This recipe card was updated August 2026 with a refreshed recipe and new photos.