STEP 8:
Whip egg yolks and slowly drizzle in hot sugar syrup. Mix until pale and fluffy. Add butter, 2 Tbsp at a time, then add Nutella, vanilla and salt.
STEP 9:
To assemble, fill cupcake center hole with Nutella. Frost cupcakes with buttercream, drizzle Nutella on top and sprinkle with hazelnut praline.