Preheat oven to 375°F. Place hazelnuts on baking sheet; bake 8 minutes or until lightly browned. Quickly transfer nuts to clean dry dish towel. Fold towel; rub vigorously to remove as much of the skins as possible. Finely chop hazelnuts using food processor, nut grinder or chef’s knife.
Increase oven temperature to 450°F. Place salmon in baking dish. Combine apple butter, mustard, thyme and pepper in small bowl. Brush on salmon; top each with nuts. Bake, nut side up, 14 to 16 minutes or until fish flakes easily with fork.