Mix sugar and butter till creamy. In a separate bowl mix the flour, cocoa, baking soda and salt. Add the eggs to the sugar and butter. Mix well. Add the flour mixture and mix well. Stir in the vanilla. Layer 1/3 of the batter into a greased Bundt pan. Spread 1/2 jar of the Nutella, pour 1/3 of the batter. Spread remaining Nutella; Top with remaining batter. Bake in a 350 degree oven for 1 hour and 25 minutes.