Prepare the Crust: In a medium bowl, combine the crushed digestive biscuits with the melted unsalted butter. Mix until the crumbs are evenly coated. Firmly press this mixture into the bottom of a 9-inch springform pan to create an even and compact layer. Place the pan in the refrigerator for 30 minutes to allow the crust to set and firm up.
Make the Cheesecake Filling: In a large mixing bowl, use an electric mixer set to medium speed to beat the softened cream cheese until it becomes smooth and creamy, about 2-3 minutes.
Incorporate Nutella: With the mixer running, add in the Nutella, powdered sugar, and vanilla extract. Continue to beat until the mixture is completely combined and silky, stopping to scrape down the bowl's sides as necessary to ensure an even mixture.
Whip the Cream: In a separate chilled bowl, whip the heavy whipping cream until medium peaks form. This should take about 3-4 minutes. Gently fold the whipped cream into the Nutella mixture using a spatula. Carefully lift and fold the mixture to maintain the light and airy texture, taking care not to deflate the whipped cream.
Combine and Pour: Once the mixture is well combined and fluffy, pour the creamy Nutella filling over the chilled biscuit crust in the springform pan. Use a spatula to smooth the top evenly.
Chill: Cover the cheesecake with plastic wrap and refrigerate for a minimum of 4 hours. For optimal texture, it's best to let it chill overnight.
Finish and Serve: Just before serving, drizzle additional Nutella over the cheesecake surface and generously sprinkle chopped hazelnuts on top for added crunch and flavor.
Slice and Enjoy: Carefully run a knife around the edges of the springform pan to loosen the cheesecake. Unclip the sides of the pan and gently lift it away. Slice the cheesecake into portions and serve chilled for an indulgent treat.