Grate and squeeze the lemons, keep the juice and the zest
Combine the two types of milk and add lemon juice step by step while whisking (no, milk does not curdle).
Choose a tray of your choice and line bottom with vanilla cookies. Pour lemon-cream mix on top. Continue until biscuits are used up and finish off with cream - as you do for Tiramisu.
Put the Carlotta into the freezer and let it chill for approx. 2 hours. Garnish with lemon zest.