Start by making the dressing. Put the dolcelatte and lemon juice in a small bowl and mash to a paste, using a fork. Stir in the milk and mint and add salt and pepper to taste.
Slice the melons into thin wedges. Alternatively, slice just 1 of the melons and use a melon baller to scoop out the flesh of the other.
Arrange the melon on individual serving plates with the slices of Parma ham. Spoon the dressing over and around the melon, garnish with mint and serve immediately.