Preheat oven to 375 degrees F. Spread the hazelnuts out on a single layer on a rimmed baking sheet and roast until dark brown and fragrant, 12 to 15 minutes, rotating the baking sheet halfway through baking. Keep a close eye on them, as they can go from perfect roasted to burnt in a short amount of time. Transfer the hazelnuts to a medium-sized bowl.

Once the hazelnuts are cool enough to handle, place a second bowl upside-down on top of the bowl with the hazelnuts. Shake vigorously for about 30 seconds to remove the skins of the hazelnuts. It may take a few times to get all of the skins off; each time, remove the hazelnuts that have lost their skin to the bowl of a food processor, then continue shaking.

Process the hazelnuts in a food processor until their oil is released and they form a smooth, loose paste, 2 to 5 minutes, scraping down the bowl often.

Add the powdered sugar, cocoa powder, hazelnut oil, vanilla extract and salt and process until fully incorporated, scraping the bowl as needed, about 2 minutes. The mixture will loosen and become glossy. Transfer the spread to a jar with a tight-fitting lid or an airtight container. You can store it in the refrigerator or at room temperature for up to 1 month.

If you want to do away with having to remove the hazelnut skins, you could purchase blanched hazelnuts, which I might try next time. I was not able to find hazelnut oil at any local grocery stores (including Whole Foods), so I ended up ordering it from Nuts.com. You could substitute walnut oil or vegetable oil, but the hazelnut oil really helps give the spread a silky smooth texture. You can substitute regular unsweetened cocoa powder for the Dutch-processed cocoa powder.

To Remove Skins and Roast: 1. For an easy method to peel hazelnuts, do the following: In a very large saucepan with high sides, bring 4 cups of water to a boil. Add 6 tablespoons of baking soda. The water will foam up. Add nuts to the boiling water and bring back to a boil. Lower temperature to medium and boil for approximately 3 minutes. The water will turn black. This is okay. 2. Meanwhile, fill a large bowl with ice water. After 3 minutes, remove one nut to test and place in the cold water. Using your fingers, rub the nut back and forth. The skin should easily slide off. If not, boil the nuts for an additional 1-2 minutes more and test again. 3. Remove from stove, drain and place in ice cold water. Rub the hazelnuts to remove skins. Dry them thoroughly with paper towels. It's a tedious process but worth it. 4. Preheat oven to 350 degrees F. Spread hazelnuts on a baking sheet and bake for 15 minutes or until the nuts have darkened. Remove and cool. Spread: 1. Place the cooled hazelnuts in a high-powered blender and puree until hazelnuts form a paste. If you don't have a high-powered blender, use a food processor. It will just take a little longer. 2. Add remaining ingredients and continue blending until very smooth. Pour into an airtight container and refrigerate. The spread will be thin but will harden when refrigerated.