Crumb Crust: Combine cookie crumbs, 1/4 cup sugar and butter. Press into the bottom and 2-inches up sides of 9-inch springform pan. Set aside.
Chocolate Layer: Combine 8 oz of cream cheese and 1/4 sugar and beat until creamy. Add 1 egg and 1/4 tsp. vanilla; blend well. Stir in melted chocolate and 1/3 cup sour cream. Spoon over chocolate crumb layer.
Brown Sugar Layer: Combine 8 ounces of cream cheese, 1/3 cup brown sugar and flour and beat until well mixed. Add 1 egg and 1/2 tsp. vanilla; blend well. Stir in pecans. Spoon gently over chocolate layer.
White Sour Cream Layer: Combine 5 oz cream cheese and 1/4 cup sugar; beat until fluffy. Add egg and blend well. Stir in remaining 1 cup sour cream and vanilla. Spoon gently over praline layer.
Bake at 325 degrees for 1 hour; turn off oven and leave cheesecake in oven for 30 minutes; open door of oven and leave cheesecake in oven an additional 30 minutes. Let cool at room temperature for 1 hour, then chill for 8 hours or overnight.
Remove from pan and make chocolate glaze.
To make the chocolate glaze combine 6 oz chopped semi-sweet chocolate and 1/4 cup butter in a small saucepan and melt over low heat. Remove from heat and stir in the 3/4 cup powdered sugar, 2 tablespoons of water and 1/4 teaspoon of vanilla until smooth. Pour over cake. Put the cake in the refrigerator to set the glaze.
At this point, the cake needs some sort of garnish. You could pile chocolate leaves on top, add nuts or do what I do and drizzle lines of melted white chocolate over the top.