Preheat oven to 375°F. Spread nuts on a baking sheet; toast for 10 minutes. Wrap nuts in a kitchen towel and let cool for 5 minutes. Rub nuts in towel to remove skins. Finely chop nuts.
Place 1/2 lb. chocolate in a saucepan and cook, stirring constantly, until melted. Remove from heat and whisk in cream, chocolate-hazelnut spread and salt. Stir in 1/2 cup chopped nuts. Let cool until thick enough to scoop with a spoon, stirring occasionally, 1 to 2 hours.
Line a baking sheet with waxed paper. Scoop 1 Tbsp. cooled mixture and roll between palms to form a 1-inch ball. Place on sheet. Repeat with remaining chocolate mixture. Refrigerate.
Place half of remaining chocolate in a saucepan and cook, stirring constantly until melted. Remove from heat and add remaining chocolate. Stir occasionally until smooth.
Set a chocolate ball on a fork and dip into melted chocolate. Let excess chocolate drip into bowl. Return ball to baking sheet. Repeat. Sprinkle balls with remaining hazelnuts. Let stand at room temperature or refrigerate until set.