After baking the crust, grease the sides of the pan.
Melt the chocolate in the microwave in 15-second bursts, stirring until smooth. Let it cool.
Beat the cream cheese for 3 minutes on medium speed until creamy.
Add the granulated sugar and beat for another 2 minutes.
Scrape the bowl, then beat for another 30 seconds.
Mix in the sour cream, then scrape the bowl again.
Add the Nutella and mix until combined.
Pour in the melted chocolate and mix well.
Scrape the bowl frequently to avoid lumps.
Add eggs one at a time, mixing just until combined after each. Don’t overmix to prevent cracking.
Stir in the vanilla and salt briefly.