I used some regular white chocolate along with the caramelised stuff, and the flavour is still lovely and rich, so I think actually it might be too rich if it were all caramelised (especially for generously-topped cupcakes).
For the cake I used TorteNZ's white chocolate mud cake recipe. The first step is melting the chocolate, butter, milk and sugar together in a saucepan, and this takes the prize for most disgusting-looking foodstuff I've ever made. But push through the pain, for the glory is to come!
The recipe is really easy (mud cakes are good like that) - there's the melting step, then you add eggs and vanilla, and then the flour. You can do the whole lot with a wooden spoon or spatula (though I confess I often whip out a whisk to make sure it's perfectly smooth, a step you can skip if you're less pedantic).
The recipe only has 1 and 2/3 cups, so I'd left out more than half the total flour for the recipe (in the original recipe some of the flour was listed as self-raising; I never use self-raising flour, instead adding baking powder to regular flour, and I knew adding flour was the last step and somehow just didn't see that last line). I had thought the batter was particularly runny but mud cake batter usually is pretty liquid so figured that was okay.
On realising my mistake I leapt up and ran to the oven to check the cupcakes, which should have been just about cooked by that stage. The middle picture above shows what I saw; bubbly liquid. Not so good. So I let them cook long enough to firm up (outcome: extremely buttery, dense and not very structurally sound cake things) then dashed to the supermarket to get some more white chocolate (I have a huge bag of Callebaut white chocolate but it works out about twice as expensive as Cadbury Dream, which tastes good and has a respectable 24% cocoa butter; hence I tend to use Dream for recipes where the chocolate is less prominent - e.g. cake - and Callebaut for cookies or uncooked things, where the chocolate flavour usually shines more).
The result? Spectacular! I LOVED the icing, as did many of my colleagues - several asked how I made it, one even told me she'll never be able to eat another cake because this was so good nothing else could live up to it. So I'll take that as a vote of approval; caramelised white chocolate is a definite win!
White Chocolate Cupcakes
300g white chocolate
1 cup milk
3/4 cup caster sugar
2 teaspoons vanilla extract
2 large eggs, lightly beaten
230g/1 and 2/3 cups flour
1 tsp baking powder
Preheat oven to 160C and line 18-20 muffin pans with cupcake papers. Place chocolate, butter, milk and sugar in a pot and melt over a low heat, stirring frequently. Allow to cool for 5-10 minutes (this prevents the egg from curdling when you add it).
Add in the beaten eggs and vanilla. Sift flour and add into the chocolate mixture. Mix until smooth.
Spoon into cupcake papers and cook for about 20 minutes (check after 15 - ovens vary!). Alternatively this batter makes a 20cm cake, which will take around 1 hour 15 minutes to cook.
Caramelised White Chocolate Ganache
275g white chocolate
200g caramelised white chocolate
Heat cream in a saucepan until just boiling. Remove from heat and stir in chocolate with a gentle folding motion until all melted and combined. Leave to cool. When thick, beat until fluffy, then pipe onto cooled cupcakes.