Toast hazelnuts in a dry skillet over medium heat for 4–5 minutes, shaking often, until fragrant.
Wrap warm nuts in a clean towel and rub to loosen skins. Reserve 18 whole; finely chop the rest.
Combine hazelnut butter, maple syrup, cocoa, vanilla, and salt in a bowl until thick and glossy.
Line a small tray with parchment. Stir chopped hazelnuts into the crushed wafers and spread in a shallow dish.
Scoop about 2 teaspoons of filling, press a whole hazelnut inside, and roll into a smooth ball.
Roll each ball in the hazelnut–wafer mixture to coat. Chill on the tray for 10 minutes.
Melt chocolate with coconut oil in short microwave bursts or a double boiler, stirring until silky.
Dip each chilled ball into the chocolate, let excess drip off, and return to the lined tray.
Chill until the shells are firm, about 15 minutes, then serve or store chilled.