• In a 9 inch springform pan, criss-cross 2 strips of parchment paper to create tabs. Then cut a circle from the parchment paper and lay it over the strips. This will make it easier to remove the tart from the pan. 
• Over medium heat, melt butter in a saucepan. Once melted, remove from heat and set aside.
• In a food processor, process the amaretti cookies until they are a fine, crumb-like texture.
• In a medium-sized bowl, mix the crushed amaretti cookie crumbs, melted butter, salt, and brown sugar with your hands until all the amaretti are evenly coated and look wet. The crumbs should hold together in a clump if you press them in your fist.
• Press the crumbs evenly and tightly into a springform pan into one layer. Place the pan into the fridge while you make the filling.
• With a stand mixer or hand mixer, whip the ½ cup of whipping cream until stiff peaks form. Set aside.
• In a stand mixer, combine the mascarpone and nutella. Whip until the two are well-blended and a cream-like consistency is reached.
• Fold the whipping cream into the nutella-mascarpone cream.
• Remove the springform pan from the fridge, and top the crust with the nutella-mascarpone filling.
• Place the tart back in the fridge and allow it to firm up for at least 2 hours, or overnight.
• Remove it from the fridge, cut into pieces, serve and enjoy!

For the whipped cream topping (optional):

• When you're ready to serve the tart, whip the whipping cream, sugar and vanilla extract until stiff peaks form. 
• Using a spatula or spoon, spread the whipping cream on to the tart, and sprinkle with chopped hazelnuts and shaved chocolate.