In a small sauce pan on medium-low heat, add the granulated sugar. You will eventually see parts of the sugar start to caramelize. Swirl the pan to incorporate the un-melted sugar grains and continue to cook until all of the sugar is completely caramelized.
While the sugar is caramelizing, take a tooth pick and stick it in a hazelnut. Continue until all of the hazelnuts are on tooth picks. Prepare a baking sheet with a sheet of parchment paper and set aside.
Once the caramel is ready, gently dip the hazelnut into the caramel, then slowly remove the hazelnut, allowing the caramel to drip down. Hold for a couple seconds allowing it to cool a tad, before transferring to the parchment paper. You can also put a heavy cutting board on the edge of the counter. Lay some parchment down on the ground under the cutting board. After dipping each hazelnut in the caramel, carefully stick the toothpick between the countertop and cutting board, allowing the caramel to drip down towards the ground. The parchment paper will catch any caramel that drips to the ground.
Continue with the rest of the hazelnuts, until all are covered in caramel.
Once you are done caramelizing the hazelnuts, take the hazelnuts off of the toothpicks and feel use a pair of scissors to trim the "tail" of the caramel to the desired size. I like to take the left over caramel webs and form them into a rough ball, which can be a nice touch on top of the tart.
Before serving, add a couple caramelized hazelnuts on top of the ganache to decorate the tart.