In a small saucepan, combine the port, sugar, cider vinegar, cloves, orange zest, cinnamon, salt and 1 cup water. Bring to a simmer over medium heat. Reduce the heat to medium-low and add the prunes; simmer until softened and plumped, about 10 minutes. Allow the prunes to cool in the poaching liquid for 5 minutes. Using a slotted spoon, remove the prunes to a plate and allow to cool completely.
Preheat the oven to 400 degrees F.
Using a paring knife, make a slit from stem to tip in each of the prunes. Stuff each with a piece of Parmesan and wrap in a quarter slice of prosciutto. Place the wrapped prunes, seam-side down, on a rimmed baking sheet.
Bake until the prosciutto is crispy and the Parmesan is soft and melted, 8 to 10 minutes. Serve warm or at room temperature.