First, roast your hazelnuts. Preheat the oven to 200 °C or 390 °F. Line a baking sheet with parchment paper and add your hazelnuts in a single layer. Place in the middle of the oven and roast for 10 - 12 minutes, then remove from the oven and wrap in a kitchen towel to remove the skin. Rub nuts in a towel to remove loose skins or use a salad spinner. Fill the salad spinner with the roasted hazelnuts and spin a couple of times until the skin loosens.
make the hazelnut chocolate spread
Add roasted hazelnuts, icing sugar, and unsweetened cocoa powder to a bowl of a stand mixer or blender. Pulse for a couple of times at high speed. After each pulse, scrape the sides and bottom of the bowl using a spatula, then pulse again until you get a sand-like mixture. It will take about 5 minutes of pulsing to achieve that. Add the canola oil and melted chocolate and mix again until combined.
Transfer your homemade Hazelnut Chocolate Spread to a jar or airtight container. Close the jar or container and store at room temperature (in your pantry) for up to a month or serve with bread, pancakes, or crepes.