Place 2 tablespoons cold water in a small saucepan; sprinkle with gelatin, and set aside to soften, about 5 minutes.
Meanwhile, in a medium bowl, whisk chocolate-hazelnut spread with 1/4 cup cream; set aside.
Heat gelatin mixture very gently over low, stirring just until dissolved; set aside.
In a large bowl, using an electric mixer, beat remaining 2 cups cream with sugar until soft peaks form. While still beating, pour dissolved gelatin mixture over cream all at once (gently reheat gelatin mixture if it has stiffened).
Fold half of whipped cream into chocolate-hazelnut spread mixture to finish the Chocolate-Hazelnut Filling; the remaining whipped cream is the Whipped-Cream Frosting.