For the chocolate crust: Preheat the oven to 350 degrees F. Line the cake pan with parchment paper. Process the cookies to a powder in a food processor (should create about 1 1/4 cups), and then add in the butter and process until the cookies are wet. Pat the crumbs into the bottom of the cake pan and bake 10 minutes. Let cool.
For the praline cheesecake: Lower the oven to 325 degrees F, and move the rack to the lower third of the oven. Cream the praline paste until smooth in a stand mixer. (The praline paste may be separated and rather stiff when removed from the can, but it should become very smooth before adding the other ingredients.) Mix in the cream cheese on low speed until well blended, scraping the bowl often. Add the sugar, cream and then the eggs, mixing well after each, and then add the vanilla.
Transfer the cheesecake mixture into the crust. Set the cake pan into a roasting pan, and fill halfway up the side of the cake with hot water. Bake until the cheesecake has set on top and no longer appears liquidy when gently shaken, 1 hour 45 minutes to 2 hours. Remove from the oven and allow the cake to cool in the water bath to slowly bring down the temperature and prevent deep cracks.
Refrigerate several hours or up to overnight. Unmold by heating the cheesecake over a flame on the stove a few seconds, and then running a thin blade around the pan and inverting the cake onto a flat plastic wrap-covered surface. Flip the cheesecake back onto a cardboard round that fits the bottom exactly. If the cardboard is too big, it will show when you pour the ganache over the cake.
For the ganache: Heat the cream until just steaming (but not boiling) in a medium pot. Turn off the heat and stir in the chocolate and butter, shaking the pot to make sure all the chocolate is submerged in the hot cream. Let sit about 3 minutes, and then gently stir the ganache until completely smooth. Do not whip any air into it or the surface of your cake will not be smooth. Allow to cool to just above room temperature and thicken, 10 to 15 minutes. If the ganache is too thin, it will just pour off the cake without coating well.
Meanwhile, place the cake on a wire rack set over a parchment-covered baking sheet to catch any ganache drips.
Pour the ganache over the cake, starting in the center and then moving to the outer edge, making sure the entire cake is covered. Very gently shimmy the wire rack back and forth so the surface of the cake smooths out. Let sit until the ganache is set up, about 30 minutes.
Decorate the top of your cake with the Candied Hazelnuts, with the points way up in the air. Cut the cheesecake using a thin blade that has been dipped in hot water and wiped clean. Enjoy!
Cook's Note: You will end up with lots of leftover ganache; it can be refrigerated about 1 week or frozen up to 1 month.
Set a heavy cutting board near the edge of a table or counter to weight down the skewers, and place parchment or newspaper on the floor below where the hazelnuts will be suspended to catch the caramel drips.
Heat the hazelnuts in a pan to remove the skins more easily if yours are not already blanched, about 1 minute. Gently stick a skewer into each hazelnut.
Bring the sugar, corn syrup and 1/4 cup water to a boil in a small saucepan without stirring. Once the mixture starts to caramelize, remove from the heat and allow to darken and thicken, stirring occasionally so it won't set up on the bottom of the pan, about 5 minutes.
Once the caramel has thickened, dip the hazelnuts on the skewers into the caramel and lift to see if the caramel is clinging. If the caramel just runs off, then you may need to wait 1 minute longer and repeat. When the caramel coats the hazelnuts and drips off in long strands, secure the skewers under the cutting board so the caramel can drip down and suspend in strands.
Let the hazelnuts sit until the caramel is well set, about 15 minutes. Break off the caramel strands at the desired length and gently twist the hazelnuts from the skewers.