Entirely Elizabeth

27 Choose your stand mixer/hand mixer attachment. The paddle for a smooth and creamy frosting. The whisk for a light and airy frosting.
17 On medium-high speed beat the room temperature unsalted butter for 3 to 5 minutes. It should be light in color and smooth.
21 Add Nutella hazelnut spread, vanilla extract, and salt. Beat on medium speed until fully incorporated, about 1 to 2 minutes.
24 Add unsweetened cocoa powder. Beat on low speed until fully incorporated, 1 to 2 minute.
18 Add half the powdered sugar, beat on low speed until it is fully absorbed within the frosting, about 1 minute. Do this again with the remaining powdered sugar.
25 Beat the buttercream on low speed while slowly pouring in the heavy whipping cream. Continue to beat until it has been incorporated.
28 Assess the buttercream's consistency. If the frosting is too thick, add an additional 1 tablespoon of heavy whipping cream until desired consistency. If the frosting is too thin, add an additional 2 tablespoons of powdered sugar until desired consistency. 
23 Assess the buttercream's texture. If too airy, use a spatula to fold by hand until it smooths out. If too dense, turn the mixer up to it's highest speed and whip the frosting for about 1 minute to aerate it.
29 Prepare Nutella Buttercream Frosting for decorating.