For cake, preheat oven to 350 °F and line the bottom of an ungreased 9-inch springform pan with parchment paper.
Melt the chopped white chocolate in a microwave on medium heat, stirring every 10 seconds until melted. Cut butter into pieces and set on top. Cover dish and allow to melt in while preparing eggs. Whip whole eggs, egg yolks and ¼ cup icing sugar with electric beaters until pale and fluffy. Stir chocolate mixture to incorporate butter and fold into egg mixture. Stir in lemon zest. In a separate bowl, whip whites with remaining icing sugar until they hold a medium peak. Fold a third of the whites into chocolate mixture and then fold in remaining two thirds. Spread into prepared pan and bake for 35 to 45 minutes, until top of cake is an even golden brown colour. Let cake cool completely. Don’t worry if the cake falls in the center – it’s supposed to (leaves more room for cream!). To remove from pan, gently run a knife around the outside edge of the cake and loosen pan. Peel off parchment and place on a platter.
For cream whip cream with icing sugar until it holds a medium peak. Fold in skim milk powder and vanilla and spoon over cake. Arrange strawberries on top and dust generously with icing sugar before serving. To create white chocolate shavings, use a vegetable peeler to scrape curls or shavings of white chocolate (the softer the chocolate, the bigger the shavings).
Cake can be made a day in advance and can be assembled up to 6 hours ahead of serving.