Preheat oven to 350 degrees. Grease a 9-inch square baking pan.
In a large bowl, combine flour, cocoa, and salt. Melt butter in a large saucepan and remove from heat. Stir in sugar and vanilla. Quickly whisk in eggs, one at a time.
Add butter mixture to flour mixture and stir until well blended. Spread brownie batter into prepared pan and bake for 25-30 minutes. Cool completely.
Meawhile, make the Nutella cheesecake layer. With an an electric mixer, beat together cream cheese, Nutella and powdered sugar until smooth.
In a separate bowl, beat cream with an electric mixer until stiff peaks form. Fold the whipped cream into the Nutella mixture. Spread over the cooled brownies.
Refrigerate for at least 2 hours before serving, or until the cheesecake layer is firm. Drizzle with melted chocolate, if desired.