Hi there, I only have butter as well in France, but can give you a recipe for white chocolate buttercream which is absolutely gorgeous. This does not need to be refrigerated, unless it is baking hot ( over 28 degrees).
100g butter, creamed
Then add 100g of melted white chocolate. You need to make sure there are no lumps in it at all.
Mix them together really well and then add 360g of icing sugar.
If this is a bit too thick, add a little bit of sterilised milk (non refrigerated kind).
This goes almost white, but add a bit of violet colouring to get it whiter if you want.
Hope this helps.
gateaux de mandy
