Preheat oven to 325°F. Place an 8 x 8 pan on bottom rack and fill halfway with boiling water.
Spray a 9 inch springform pan with cooking spray. Wrap outside of pan with aluminum foil. Set aside.
In a medium-size mixing bowl toss together graham cracker crumbs with sugar and butter until fully moistened. Press onto bottom and halfway up sides of pan. Place pan into freezer while you make filing.
Meanwhile, to melt chocolate for filling, place in a small saucepan . Cook, over very low heat stirring occasionally, just until melted. Do not boil. Or, place chocolate in microwave-safe bowl. Microwave in 30 second increments on 50% power, or using the melt function, stopping to stir occasionally. Repeat, until melted. Cool slightly.
Using an electric mixer, whip together cream cheese, sugar and vanilla until completely smooth. Add eggs one at a time mixing well after each addition. Scrape sides and bottom of bowl as needed.
Add melted chocolate, cream, cocoa and cornstarch. Mix just until fully combined on medium speed, without beating too much air into the filling.
Pour evenly into crust. Bake on middle rack of oven for 1 hr 15 minutes - 1 hr 30 minutes or until the center is still just slightly loose when gently shaken. It won't be completely set. Turn off oven, leave door slightly ajar, and leave cheesecake in oven for 1 hour longer to gently finish baking.
Remove to a cooling rack, and allow to cool for 30 minutes then run a knife gently around the top edge. Cool completely on rack to room temperature with ring in place. Cover and chill for 12 hours or overnight.
To make ganache: Place chocolate chips in a mixing bowl. Heat cream on the stovetop for 2-3 minutes, just until it comes to a boil. Don't walk away, it will boil over quickly. Pour over chocolate chips. Let sit 3-5 minutes, then stir until smooth. Allow to cool for a few minutes just until warm but, still pourable.
Remove ring from cheesecake. Pour ganache on cheesecake, allowing to drip over sides. Immediately place into fridge and chill just until ganache is set, 1 hour.
Sit on counter for 1 hour prior to serving with whipped cream and fresh raspberries.