In a large moving bowl whip cream until stiff peaks form. Add mascarpone cheese, powdered sugar, and 2 tablespoons of limoncello. Use mixer to blend until completely combined.
In a medium size bowl or pan combine remaining limoncello with the milk. Dip each ladyfinger into the mixture for a few seconds (one at a time). Flip to coat both sides.
Arrange ladyfingers on a platter or in a pan in a configuration of 12 (or 6 if you have a deeper, smaller pan). Carefully spread half the mascarpone cheese mixture over the lady fingers (or 1/3 of the mixture if your bottom layer is smaller). Repeat these layers, alternating the direction of the ladyfingers so that it doesn’t fall apart when served. Smooth the top layer of mascarpone as flat as possible.
Garnish with lemon zest and refrigerate at least 6 hours or overnight.
