• Preheat to 350º F. Spray a 12-cup Bundt pan with baking spray with flour and set aside. (You can also use butter and flour, but I've had better luck with bundt pans well coated with baking spray with flour.)
• In a small saucepan, combine the butter, cocoa powder, salt, and water and cook over medium heat, whisking constantly, just until melted and combined. Remove from the heat and set aside.
• Combined the flour, sugar, and baking soda in a mixing bowl. Add half of the melted butter/chocolate mixture and mix until blended (it will be very thick). Mix in the remaining butter mixture. Add the eggs. Mix in the sour cream and vanilla until smooth.
• Pour the mixture into the prepared pan and bake until a toothpick inserted into the center of the cake comes out clean, 50-60 minutes.
• Let the cake cool in the pan for 15 minutes and then invert onto a rack. Let cool completely before making the glaze.

For the Glaze:

• Put the chopped chocolate and corn syrup in a medium bowl and set aside.
• Combine the heavy cream and sugar in a small saucepan, cook over medium heat, stirring constantly until the cream is hot and steaming and the sugar is dissolved.
• Pour the hot cream over the chocolate and whisk until melted and smooth. If it’s very runny, let it sit for a minute or so to thicken. Drizzle over the cake.