Preheat oven to 325 degrees. On a parchment-lined rimmed baking sheet, make 12 clusters by arranging 4 cashews and 1 hazelnut (the cashews will be the tortoises' legs, and the hazelnuts, the heads). With your fingers, gently flatten caramels and place one on top of each cluster.
Bake until caramels just begin to melt, 6 to 8 minutes. Meanwhile, microwave chocolate in 10-second increments until melted. Dollop 1 teaspoon chocolate onto each caramel and top with a pecan. Refrigerate until chocolate sets, about 30 minutes (or up to 2 days). Bring to room temperature before serving.
Have fun making these cute chocolate tortoises. Give them as gifts or put them on a party platter -- unlike their namesakes, they'll go fast!