1. For crust, heat oven to 350 degrees F. Tightly wrap the outside of a 9-inch springform pan with foil. Combine pecans, the brown sugar, and melted butter in the pan until well mixed; press into bottom. Set aside.
2. For filling, beat cream cheese in a large mixer bowl at high speed until smooth, scraping side of bowl with a rubber spatula. Beat in 2 cups sugar and cornstarch until light and fluffy. Reduce speed to low; beat in bourbon and vanilla. Add eggs, one at a time, beating until blended and mixture is smooth. Pour filling into pan. Place springform pan in a roasting pan (make sure there is at least 1 inch of space between the springform and roasting pans). Add enough hot water to come halfway up the side of the springform pan.
3. Bake 1 hour 30 to 40 minutes, until sides of cheesecake are firm and center is just set. Remove pan from water bath; transfer to a wire rack and cool completely.
4. Meanwhile, for topping, combine chocolate and cream in a medium saucepan. Cook and stir over medium-low heat until chocolate is melted and smooth. Remove from heat; cool to room temperature. Spread topping over cheesecake. Cover with plastic wrap and refrigerate 6 to 48 hours. Run a knife around side of pan to loosen. Remove springform ring. Makes 16 servings.