Rich and moist chocolate cupcakes topped with a creamy, dreamy Nutella frosting and toasted hazelnuts.
Preheat oven to 350°F/180°C. Line a muffin tin with cupcake liners and set aside.
In a standing mixer fitted with the paddle attachment, beat together butter and sugar on medium speed until light and fluffy, about 2-3 minutes. Scrape down the sides and bottom of the bowl as necessary. On medium speed, beat in eggs, one at a time, beating well after each addition. Add vanilla extract and beat until combined. With the mixer on low speed, add half of the dry ingredients and beat just until combined. Beat in milk until combined. Add the other half of the dry ingredients and beat slowly until combined. Add hot water and beat just until combined. Do not over mix—the less you mix, the lighter the cake will be. The batter should be liquid. Fold in hazelnuts if using.
For the frosting: In the bowl of an electric mixer fitted with the paddle attachment, beat butter at medium speed until pale and fluffy, about 2 minutes. Add powdered sugar in 2 additions and beat until completely smooth. Add Nutella, vanilla extract, and heavy cream, and beat until combined and creamy. Add powdered sugar as necessary until frosting is spreadable. Frost cupcakes once they’ve cooled, then top with toasted hazelnuts. Use frosting immediately to frost cupcakes or store in the fridge, covered, for up to 3 days. Before using, bring to room temperature and beat or whisk by hand until smooth again, about a minute.
*To toast the hazelnuts, place them in an even layer on a pan lined with parchment paper. Bake in a preheated oven at 350°F/180°C for 5-8 minutes.