Gently warm the nutella by placing the bottle in a pan of hot water. The nutella should be runny and spreadable. Spread a Tablespoonful in the bottom of each of the tartlet crusts and chill while preparing the filling.
In a large mixing bowl, combine the pumpkin, milk, eggs, syrup, sugar, and spices, and whisk until smooth and evenly blended. Remove the tartlets from the fridge and gently spoon the pumpkin mixture over the nutella. Place the tartlets on a baking sheet to catch any spills. Sprinkle each tartlet with 1/2 Tbs of chopped hazelnuts.
Bake at 350 for about 30 minutes, or until the filling is set and a knife inserted into the center comes out clean. Cool on a rack until ready to serve, with a puff of whipped cream, of course.