01 - Puree the diced mangoes with lime juice and sugar in a blender until completely smooth. Set aside for assembly.
02 - Beat the mascarpone cheese, powdered sugar, and vanilla extract in a large bowl with an electric mixer until smooth and creamy, about 2 minutes.
03 - In a separate chilled bowl, whip the heavy cream to stiff peaks using a hand mixer or whisk. The cream should hold its shape when the whisk is lifted.
04 - Gently fold the whipped cream into the mascarpone mixture using a spatula. Incorporate slowly until fully combined and fluffy, taking care not to deflate the cream.
05 - Combine the cooled coffee with rum or mango juice in a shallow dish wide enough to dip ladyfingers.
06 - Quickly dip each ladyfinger into the coffee mixture for 1-2 seconds per side—do not soak. Arrange in a single layer at the bottom of an 8x8 inch dish or individual serving glasses.
07 - Spread half of the mango puree evenly over the ladyfingers, followed by half of the mascarpone cream. Use an offset spatula to smooth the surface.
08 - Repeat with another layer of dipped ladyfingers, remaining mango puree, and remaining mascarpone cream. Smooth the top surface evenly.
09 - Cover tightly with plastic wrap and refrigerate for at least 4 hours, preferably overnight. This allows flavors to meld and the texture to set properly.
10 - Just before serving, arrange thinly sliced fresh mango on top and garnish with fresh mint leaves. Serve chilled directly from the refrigerator.