SUPER IMPORTANT: The recipe varies slightly depending on whether you're using the frosting for piping on cupcakes or to use in layer cakes. The default ingredients list and method steps are for piping frosting on cupcakes. Variations for layer cake frosting will be in brackets. For layer cakes, make this recipe for the 1st layer of cake and let it sit in the fridge overnight. The next morning, make 1.5 times of this recipe as if you're making it for cupcakes (super important!), to frost the second layer of cake and the sides. This frosting doesn't work for cakes taller than 2 layers, but they can be up to 5cm (2-inch) thick layers.

First make your white chocolate ganache. Finely chop the white chocolate. Put it in a small bowl (or mug) with 15 g of the whipping cream. Melt it in the microwave in 2 x 30 second bursts. Stir it till smooth and put it in the fridge to cool down. If I'm in a rush I scrape it onto a plate and put in the freezer for 5 minutes. (*If making frosting for your 1st layer of cake, skip the ganache! Instead, stir ½ tsp agar-agar powder and 3 Tbsp water together in a small saucepan and set aside for 10 minutes. Once it's hydrated, boil the mixture for 2 minutes and set aside to cool slightly.)

Whip the remaining COLD cream to soft peaks with an electric hand mixer in a medium mixing bowl. (*If making frosting for 1st layer of cake, whip all 80 g of cold cream to soft peaks.)

Beat in COLD Cream Cheese till smooth. Scrape down sides of bowl and beat again till smooth and thickened. About 1 minute in total.

Beat in Vanilla and icing sugar for 20 seconds (*if making frosting for a layer cake, beat in 20 g extra icing sugar). Leave frosting to stand in the fridge for 5 minutes so that sugar can melt into the cream cheese thoroughly.

Get the frosting from the fridge. Beat it on max speed for 30 seconds - 1 minute (tilt your bowl and keep your beaters still in on the lowest side of the bowl while beating). The frosting might start off runny, but keep beating in one spot and it will start to thicken up. You're essentially re-whipping the cream inside the frosting. It should be quite thick after 1 minute. *NOTE: If the frosting isn't COLD, it won't whip up.

Next scrape all the white chocolate ganache (it shouldn't be warmer than a cool room temperature when you add it in) into the frosting and beat it in on max speed immediately for 1 minute. The white chocolate will also help to thicken up the frosting even more. (*If making frosting for 1st cake layer, scrape your room temp, liquid agar-agar mixture into your frosting and beat it on max speed for 1 minute.)

The frosting will be quite thick at this stage (depending on the cream cheese you used and how cold your ingredients were). If I’m using the frosting for layer cakes, I use it as it is. Frost the first layer of cake and let it chill in the fridge for AT LEAST 4 hours (I leave them in the fridge over night). Note that this is NOT a hard setting frosting. It will always still be wet to the touch, but it still holds.

FOR LAYER CAKES: When the first layer of frosting has firmed up a bit, you can add 1 more cake layer on top. Not ideal for stacking more than 2 layers of cake!! Make 1.5 times this recipe and frost the top and sides of the cake. When you've frosted the outside of the cake, let it stand in the fridge for at least 2 more hours. After that the frosting is quite stable at room temp and won't melt - even on a hot day!

If I’m piping the frosting onto cupcakes, I like to leave the frosting at room temperature for a few minutes to soften slightly before I transfer it to a piping bag. When you've frosted your cupcakes, let them stand at cool room temperature (or in the fridge) for about 30 minutes. After this the frosting is quite stable and won't melt - even on a hot day! I even tested this on a day that was 43 degrees C (109 degrees F).