Preheat the oven to 350 degrees.
Place the hazelnuts in a roasting pan, and roast for 10 minutes. (You can skip this step if your hazelnuts are already peeled.)
Cool the hazelnuts and remove the skins. You can do this by pressing on them with your hand, using a rolling motion. If the skins are stubborn, submerge the nuts in water and then peel them. (You don't need to get every last bit of the peels off.)
Add the oil to the blender, then add the hazelnuts. Turn the blender on, and gradually increase the speed to medium. Process for one minute (or more), or until a smooth nut butter is formed. You may need to scrape down the sides or use a tamper to keep the ingredients moving properly.
Once the mixture is fairly smooth, add the chocolate chips gradually through the opening on top while the blender is running on low. Once all the chocolate chips are added, process for another minute on low to medium speed, scraping down the sides as needed to yield a smooth product.
Set aside briefly to cool at room temperature or in the refrigerator. The mixture will thicken as it cools.
Store this homemade Nutella in an airtight container in the refrigerator. This will keep for several weeks. The mixture will solidify to a fudge-like texture in the refrigerator. To use it as a spread, you can microwave a portion for 20 seconds, or return the full batch to the blender and process for 30 seconds.