Line a large baking sheet with parchment paper
In a microwave safe bowl melt dark chocolate chips. Use chocolate melt setting, or reduce power to 50%. Stir every 20-30 secs to avoid burning the chocolate. (Optional, melt chocolate over a double boiler).
Pour dark chocolate onto parchment lined baking tray and spread to an even thickness with a spatula. No science here - just don't go too thin or the bark will be fragile.
Repeat with the white chocolate, melting carefully in the microwave or over a double boiler. Use a clean bowl!
Using a large spoon, randomly add scoops of white chocolate over top of the dark chocolate on the baking tray and swirl into the dark chocolate using a knife.
Sprinkle granola evenly over the chocolate, pressing lightly into the chocolate.
Allow to harden completely, one hour in the refrigerator - then break into chunks.
Will keep in a covered container in the refrigerator for several days.