To make the ganache, in a small saucepan, cook the raspberries over low heat, stirring often, until the berries break down and the juice thickens, about 6 minutes. Transfer the berry mixture to a blender and process on low speed until smooth, about 20 seconds. Set a fine-mesh sieve over a medium bowl; using a rubber spatula, push the berry mixture through the sieve. Place the chocolate in a small microwave-safe bowl. Microwave chocolate on high in 30-second intervals, stirring thoroughly between intervals, until melted and smooth, about 1 minute 30 seconds. Stir 1/4 cup of the raspberry puree into the melted chocolate until smooth. Pour the ganache on top of the caramel and spread into an even layer with a small offset spatula. Let sit until the chocolate and caramel set, at least 4 hours. (As an alternative, chill for 45 minutes to set.) Lift out on parchment, slice into 1 3/4-by-1-inch bars, and serve.