These granola bars are fantastic for an on-the-go-breakfast, a delightful mid-day treat, or a fun midnight snack! Whenever you eat them, you'll be wowed by the delicious explosion of flavor!
Preheat the oven to 375°F, and place the hazelnuts in a single layer on a baking sheet.
When the oven is preheated, roast them until they are very aromatic and the skins are cracking, about 5 minutes. Let them cool for at least 5 minutes, and then they can be rubbed together in your hands, or in a dish towel, and the skins should flake away. (Some tiny bits of skin will remain, and that's okay.) Roughly chop the nuts and set them aside.
Turn the oven down to 350°F, and line two baking sheets with parchment paper.
Use a spatula to help you "pour" the granola mixture onto one of the parchment-lined baking sheets. Use a flat-bottomed metal spatula to flatten out the mixture. It should be about ½-inch thick and cover the sheet. Go around the edges with the metal spatula to make them straight.
Roast in the preheated 350°F oven until it's a dark golden brown, about 30 minutes.
With a Chef's knife, cut the cooked granola into about 27 evenly sized, rectangular bars.
Place the cut granola bars on the second, parchment-lined baking sheet, with 1 to 2 inches between them. Now use a small spoon to drizzle the melted chocolate over the bars. (This will work the best if your chocolate has just been melted and is still very warm.)
Place the chocolate-drizzled bars on a large plate or platter to let the chocolate cool and harden completely. This might take an hour or so at room temperature. To speed it up, you can place the baking sheet in the refrigerator for about 10 minutes.