Place hazelnuts in a single layer on a baking sheet and roast for 10 minutes in the 350 F hot oven.
While roasting the nuts, melt cacao butter in a double boiler (or if you don't have one, in a heavy bottomed sauce pan on the absolute smallest flame or on extra low low low, while moving it all the time). Remove from heat as soon as 3/4th melted and continue moving around until the last bit melts.
Mix in cocoa powder until fully dissolved, then add maple syrup and mix well.
Process roasted hazelnuts in your food processor until flour like consistency and then add cacao butter, cocoa maple syrup mixture to the hazelnut flour. Continue processing until well combined.
The Nutella will be quite liquid at this point. Pour into a sealable glass container and refrigerate for 4 hours or until spreadable consistency.