Remove the seeds and cut the flesh from the watermelon (300 g), 1 honeydew melon, and 1 Galia melon into roughly 1-2 cm cubes. Try to keep roughly equal amounts of each melon variety for varied color in the layers.
Squeeze 1 lemon and toss the melon cubes with the juice.
Zest the second lemon and squeeze out its juice. In a bowl, combine the mascarpone, ricotta (or quark), honey, lemon zest, and lemon juice. Stir in the wine (Vin Santo or sherry). Taste and adjust the seasoning by adding more honey, lemon juice, or wine as needed.
In a large glass bowl, layer the ingredients: start with melon cubes, then add broken Cantuccini biscuits, then mascarpone cream. Repeat this pattern until the bowl is almost full, finishing with a layer of mascarpone cream on top.
Arrange the remaining melon cubes in a pile in the center of the trifle. Place Cantuccini pieces around them as desired. Garnish with fresh mint or lemon balm.