Bring the prune juice to a boil, then reduce to a simmer for about one hour, occasionally scraping down the sides.

While the prune juice is reducing, prepare the remaining ingredients. Also, grease a loaf pan and add two strips of parchment paper to completely cover the bottom of the pan and sides. Also, cut 64 pieces of wax paper into roughly 4-inch squares.

Cook down the juice until it reaches a slightly thick, syrupy consistency and yields about ½ cup. Swipe your finger across a rubber spatula to feel the consistency of the reduction.

Once the juice has reduced, add the butter, granulated sugar, brown sugar, and heavy cream, stirring to combine.

Turn the heat to medium and bring the mixture to 255℉, stirring occasionally. Once the caramel reaches temperature, remove it from the heat and stir in vanilla and salt.

Pour the caramel into the prepared pan, spread the minced pistachios on the top, and place it into the fridge (uncovered) for about two hours.

Once the caramel has solidified, carefully coat the blade of a sharp chef's knife with neutral oil, such as grapeseed oil, and cut into the desired sizes. Add a swipe of oil to the blade in between each cut.

Separate the caramels immediately (keeping them on parchment or wax paper) so they don't stick together, then wrap each caramel individually in wax paper.