In a small saucepan combine the chocolate, cream, and butter. Stir over low heat until the chocolate is melted. Transfer to a small bowl and let cool for 15 minutes. Cover and freeze about 1 hour, or until fudge-like consistency. Divide chocolate filling into 20 equal portions about 2 teaspoons each and roll into balls. Place in freezer.

Preheat the oven to 350°F. Line 2 standard muffin tins with 20 paper liners. In a medium bowl whisk together the flour, baking powder, baking soda, salt, cinnamon, ginger, and nutmeg. In the bowl of an electric mixer, beat the butter and brown sugar until light and fluffy, about 3 minutes. Add the eggs, one at a time, and beat until combined. Add in the vanilla and sweet potatoes. Add the flour mixture and buttermilk alternatively, beginning and ending with the flour. Beat just until combined. Divide half of the batter among the cupcake cups. Place a ball of chocolate into the center of each cup. Top evenly with the remaining batter. Bake 18 to 20 minutes. Cool completely.

Combine the caramel candies and 2 tablespoons of milk in a microwave-safe bowl. Microwave in 30-second bursts, stirring between bursts, until the caramels are melted. Stir in the salt. Let cool until the sauce is soft but still pliable. In the bowl of an electric mixer, beat the butter, cream cheese, and vanilla until light and fluffy, about 3 minutes. Gradually add the powdered sugar and the remaining 2 tablespoons of the milk and beat until very well combined, about 2 minutes. Beat the cooled caramel sauce into the frosting until combined. Spread over cupcakes. Serve or store in an airtight container in the fridge for up to 2 days. Bring to room temperature before serving.