If you're making a homemade crust, make the pie crust according to the instructions. Once you have your pie crust made and rolled out, press it into a sprayed 9-inch deep-dish pie pan. “Dock” the crust by pricking it with a fork so that it doesn't bubble up.
1 9-inch deep dish Homemade pie crust
Next, refrigerate the crust for 2-3 hours or freeze for about an hour. You want to be sure the crust is very cold. When the crust is cold proceed with the pie.
Preheat oven temperature to 425°F.
To make the filling, combine the sugar and flour in a large mixing bowl. Add the melted butter, vanilla extract, eggs, and buttermilk. Use a silicon spatula to gently combine the ingredients. Don’t over mix and add too much air.
1 and ¾ cups sugar, ¼ cup all-purpose flour, 6 tablespoons unsalted butter, 1 teaspoon vanilla extract, 2 large eggs, ¾ cup buttermilk
Gently stir in the chocolate hazelnut spread until combined.
7 tablespoons Nutella spread
Pour the pie filling into the cold crust. Bake for 10 minutes at 425℉. Reduce the oven temperature to 325°F and bake for another 35-45 minutes. Add a pie crust shield or foil about half way through, if needed.
Remove the pie from the oven and set on a wire rack to cool for 1-2 hours, until room temperature. Don't cover until completely cool.
Cover the pie and place in the fridge to cool completely about 4 hours. This pie can be made 1-2 days ahead and refrigerated until ready to serve. It's best eaten in 4 to 5 days of making.