1
: Place cold coffee in a shallow bowl.
2
: Beat mascarpone, sweetened condensed milk and vanilla until well combined. Reserve.
3
: Whip cream in a large bowl until it holds stiff peaks. Gently fold into reserved mascarpone mixture until combined.
4
: Dipping both sides of each ladyfinger into cold coffee, line bottom of a 9" x 13" (3L) baking dish with 18 ladyfingers in 3 rows, trimming edges if necessary. Spread half the mascarpone filling (about 2 cups/500mL) on top. Dip remaining ladyfingers in coffee and arrange over filling in pan. Spread remaining mascarpone filling on top and sprinkle with chopped chocolate.
5
: Chill, covered, at least 4 hours.