1Prepare a cake pan by covering the sides with plastic wrap, put it in the freezer. In a bowl, mix the concentrated milk and the juice and zest of the lime. Beat the cream into a firm whipped cream, then gently stir in the lemon mixture. Crush dry cakes to obtain a fine powder.
2Remove the cake mold from the freezer, place 1/4 of the lemon mixture, smooth the surface with the back of the spoon. Place 1/4 of the cake powder on top. Put in the freezer for 10 minutes. Repeat for another 3 times and let stand in the freezer 10 minutes each time. Keep the cream in a cool place covered with a plastic wrap while you work. Do not exceed the time between each layer as the cream will lose its texture. When you spread a new layer, always smooth in the same direction to avoid the risk of moving the cake powder with your spoon.
3Freeze this semifreddo one night minimum. To unmold it, turn your cake mold over a plate, cover for 3-4 minutes with a cloth dampened with very hot water. Peel off the plastic wrap, slice the semifreddo but wait 5 minutes before the serving so the texture will be perfect.