Place ½ cup milk in a shallow bowl and sprinkle with the gelatin powder. Let soften for 5 minutes.

While gelatin is softening, pour the rest of the milk into a saucepan on medium heat. Add Nutella and stir until Nutella melts and blends with the milk. Add the milk/gelatin mixture and stir until gelatin dissolves. Remove from the heat and stir in the vanilla and a pinch of salt.

Pour into 6 ramekins (each will hold a ½ cup). Chill in refrigerator for at least 2 hours, but preferably overnight.

While the panna cotta is chilling, make the candied hazelnuts. Preheat oven to 325. Line a baking sheet with parchment paper or coat with cooking spray. Combine hazelnuts with agave nectar, brown sugar, and a pinch of salt in a bowl. Spread in a single layer on the baking sheet, breaking up clumps. Bake for about 15 minutes. Remove from oven and cool completely on the baking sheet. Store in an airtight container.