Preheat the oven to 350 degrees F. Using a pencil, draw an 8 by 10-inch rectangle on a piece of parchment paper placed on a sheet pan. Turn the parchment paper over so the pencil mark doesn't get into the chocolate.
Place the walnuts in 1 layer on another sheet pan and bake for 8 minutes. Set aside to cool and then chop roughly into large pieces.
Place 3/4 of the chocolate in a glass bowl and place it in the microwave on high power for 30 seconds. (Don't trust your microwave timer - time it with your watch.) Stir with a rubber spatula. Put it back in the microwave for another 30 seconds and stir again. Continue to heat and stir every 30 seconds until the chocolate is just melted. Immediately, add the remaining chocolate and allow it to sit at room temperature, stirring often, until it's completely smooth. (If you need to heat it a little more, place it in the microwave for another 15 seconds at a time.)
Pour the melted chocolate onto the parchment paper and spread it lightly into the drawn rectangle. Sprinkle the top evenly with the cooled walnuts, the cranberries and apricots. Set aside for at least 2 hours until firm, or refrigerate for 20 minutes. Cut the bark in 16 pieces and serve at room temperature.