Directions

1. 1

   Preheat your oven to 350°F. Grease a 9x13x2-inch baking pan with butter or non-stick spray and set aside.

2. 2

   Combine the toasted hazelnuts with 1/4 cup of the flour in a food processor. Pulse until the hazelnuts are finely ground into a powder.

3. 3

   In a separate bowl, whisk together the remaining 2 1/4 cups of flour, baking powder, baking soda, salt, and the ground hazelnut mixture. Set this dry mixture aside.

4. 4

   Using an electric mixer on medium speed, beat the softened butter, granulated sugar, and brown sugar together until the mixture is light and fluffy, about 2-3 minutes.

5. 5

   Add the 1/2 cup chocolate-hazelnut spread and vanilla extract to the butter mixture. Beat until well combined.

6. 6

   Add the eggs one at a time to the mixture, beating well after each egg is added.

7. 7

   Reduce the mixer speed to low. Alternate adding the flour mixture and sour cream in portions—add one-third of the flour mixture, then one-half of the sour cream, then another one-third of flour, then the remaining sour cream, and finish with the last one-third of flour. Mix just until each addition is combined; do not overmix.

8. 8

   Pour the batter into the prepared pan and spread it evenly with a spatula.

9. 9

   Bake for 25 to 30 minutes, or until a toothpick inserted into the center comes out clean or with just a few moist crumbs. Let the cake cool completely in the pan before frosting.

10. 10

    For the frosting: Using an electric mixer on medium speed, beat the softened butter, softened cream cheese, and 3/4 cup chocolate-hazelnut spread until the mixture is smooth and creamy.

11. 11

    Gradually add the sifted confectioners' sugar while mixing, beating until the frosting is smooth and spreadable.

12. 12

    Spread the frosting evenly over the cooled cake.

13. 13

    Garnish the top of the cake with coarsely chopped toasted hazelnuts.