1. Toast hazelnuts in a large, deep skillet over medium heat, stirring constantly, 3 minutes or until fragrant. Remove nuts from skillet.
2. Melt butter in skillet; stir in anchovy and garlic. Cook, stirring constantly, 1 minute or until garlic is toasted and anchovy has broken apart. Add chard, in batches, stirring until wilted. Cook, tossing occasionally, 15 minutes or until tender. Stir in sherry vinegar and nuts. Season with kosher salt and black pepper to taste.