01 - Blend diced mangoes with lime juice and sugar until completely smooth. Reserve in refrigerator until assembly.
02 - Combine mascarpone cheese, powdered sugar, and vanilla extract in a large bowl. Beat with electric mixer until completely smooth and creamy, about 2 minutes.
03 - In a separate chilled bowl, whip heavy cream until stiff peaks form. Gently fold whipped cream into mascarpone mixture until fully incorporated and fluffy.
04 - Combine cooled coffee with rum or mango juice in a shallow dish wide enough for dipping ladyfingers.
05 - Quickly dip each ladyfinger into coffee mixture for 1-2 seconds per side. Arrange in single layer at bottom of 8x8 inch dish. Spread half the mango puree over biscuits, then top with half the mascarpone cream.
06 - Repeat with remaining dipped ladyfingers, mango puree, and mascarpone cream. Use spatula to smooth top surface evenly.
07 - Cover tightly with plastic wrap and refrigerate for minimum 4 hours, preferably overnight, to allow flavors to meld and texture to set properly.
08 - Top with thinly sliced fresh mango and mint leaves just before serving. Slice into squares and serve cold.