Line a baking sheet with foil, shiny-side up; smooth out the creases. Make sure all your tools are dry.
Chop the bittersweet and white chocolate into 1/2-inch pieces with a large knife. Place all but 1/2 cup of the bittersweet chocolate in a microwave-safe bowl. Microwave 15 seconds, then stir with a rubber spatula. Continue microwaving and stirring at 15-second intervals until melted, about 3 minutes total. Immediately add the reserved chopped bittersweet chocolate to the bowl; stir vigorously until melted and shiny. Repeat with the white chocolate in a separate bowl. Don't worry if there are a few small unmelted pieces.
Pour the 2 chocolates side by side onto the prepared baking sheet; use the rubber spatula to swirl them together and spread into a 10-to-12-inch circle, about 1/4 inch thick.
Press the almonds and apricots into the chocolate, arranging them so each bite has a mix of flavors and textures. Sprinkle with fennel seeds. Let the bark harden completely at room temperature, about 1 hour. (If the room is warm, you may need to freeze the bark for a few minutes.) Break into pieces and store in an airtight container at room temperature for 1 to 2 weeks.