Mix the caster sugar and cinnamon together. Cut the wonton wrappers into quarters, brush with the melted butter and coat with a layer of the spiced sugar.
Put on a baking sheet and bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 2–3 minutes until crisp and golden. Leave to cool on a wire rack.
Beat the mascarpone with the icing sugar and lemon juice in a bowl and spread a little over 12 of the crisp wontons. Top with half the strawberry slices. Repeat the process with another 12 wontons and the remaining mascarpone mixture and strawberries to make a second layer. Put the remaining wontons on top and dust with a little extra icing sugar. Serve with glasses of champagne, if you like.