Preheat oven to 350°F (175°C). Spray a 12-cup Bundt pan with cooking spray. Dust with breadcrumbs.
Whisk together the flour, baking powder, baking soda, and salt. Set aside.
Using an electric mixer on medium speed, beat the sugar and butter until light and fluffy. Add the eggs, one at a time, mixing well after each addition. Mix in the vanilla and sour cream.
Gradually add the flour mixture, mixing just until combined.
Transfer half of the batter into the prepared pan, and spread evenly. Sprinkle evenly with the hazelnuts.
Drop the chocolate-hazelnut spread by small spoonfuls on top of the nuts.
Spoon the remaining cake batter over the chocolate-hazelnut spread. Using a knife, swirl the batter and Nutella.
Bake for 55-60 minutes, or until a pick inserted into the center comes out clean.
Cool in the pan on a wire rack for 15 minutes. Then, remove the cake from the pan to a wire rack to cool completely. Sprinkle with confectioners' sugar.