In a small saucepan, melt 5 tablespoons butter. In a medium bowl, combine graham cracker crumbs and 1/4 cup sugar. Stir in melted butter until crumbs are moist. Pour mixture into a 9-inch springform pan; press firmly, forming a 1/2-inch crust up sides of pan. Bake until set, 12-15 minutes. Transfer to a wire rack.
Reduce temperature to 275°F In the bowl of an electric mixer fitted with the paddle attachment, beat cream cheese until smooth. Slowly add remaining cup sugar. Scrape in vanilla seeds; reserve pod for another use. Beat until well combined, about 3 minutes.
Drizzle in eggs, one at a time, stopping occasionally to scrape down bowl, Beat in sour cream and salt, Pour batter into crust.
Bake cheesecake until sides have set but center appears soft, about 1 hour 45 minutes. Transfer pan to a wire rack to cool. Run a paring knife around the ourside of crust, loosening it from pan. When cool, cover tightly with plastic; let set at least 4 hours or overnight.
To serve place chocolate, remaining 2 tablespoons butter, and cream in top of double boiler, or a heat-proof bowl set over a pan of gently simmering water, Srir occasionally until melted. Remove from heat; let cool slightly. Pour chocolate glaze over cheesecake; spread into a circle, leaving a 1/2-inch border. Chill just until chocolate has set, about 10 minutes.