Fluffiest White Chocolate Icing is silky smooth, melt-in-your-mouth icing. It is satiny smooth, less sweet, and quite unusual. It's made with a sweet white chocolate roux and mixed with butter until light and fluffy.
In a small saucepan stir flour and sugar together. Whisk in the milk. Place the pan over low heat and cook until the mixture begins to heat up and the sugar begins to dissolve. Add white chocolate baking chips and whisk until the chips melt. Continue mixing until the mixture thickens and begins to bubble.
Remove from the heat and stir in vanilla. Pour the mixture into a bowl. Cover with plastic wrap. Press the plastic wrap (or waxed or parchment paper) against the top of the hot mixture. Refrigerate until completely cool. This can be made a few days in advance and kept in the refrigerator until ready to use.
Remove butter from the refrigerator to soften. Don't let the butter warm too much. Just until your finger presses into the butter easily and the hole still holds its shape.
In a large mixing bowl beat the butter until very light yellow and fluffy. Begin to add the white chocolate roux one heaping tablespoon at a time. Beating and whipping the after each addition. Once all of the roux has been incorporated into the butter, add the vanilla and a pinch of salt. Continue mixing for another 3-4 minutes. The icing is now ready to use.
Carefully spoon icing into a pastry bag fitted with the desired tip. Pipe swirls onto cupcakes. This should be enough to ice 18 -20 cupcakes depending on how thick you pipe the icing.
Alternatively, spread icing on cupcakes with a spatula or butter knife.
*Nutrition facts are only calculated for the White Chocolate Icing. They do NOT include nutrition for the cake.