carefully twist off the nut (the seed) from the top of the Merey (Cashew apples). Slice off the very bottom tip of the fruit; this exposes the flesh and helps it absorb the caramel syrup later.
Prick the fruit pulps all over with a fork. Gently squeeze them with your hands to wring out some of the bitter natural juices (this step is crucial to remove the mouth-drying "astringency" common in raw cashew fruit).
Place the fruit in a pot of water and bring to a boil. Cook briefly to soften, then drain the water and set the fruit aside.
In a clean pot, melt the grated Panela with a little water to create a light syrup (a miel). Add the blanched fruit into this syrup.
If using, add the splash of wine and cinnamon now. Let the mixture simmer over low heat. The goal is a slow reduction.
Continue cooking until the syrup thickens considerably and permeates the fruit. The Mereys are ready when they look dark, shiny, and shriveled, similar to the texture of a raisin or dried fig.
Remove from heat and let the sweet rest until it reaches room temperature. Transfer to the refrigerator. This dessert is traditionally served cold.