Preheat oven to 350°F. In medium bowl combine Dark Chocolate Cheesecake Bar Mix packet 1 and ½ cup softened butter. Mix until crumbly. Evenly press dough into a greased 9-inch springform pan. Bake 15 minutes. Cool slightly. Reduce heat to 325°F.
In large bowl, whisk softened cream cheese until smooth. Add Dark Chocolate Cheesecake Bar Mix packet 2 and ½ cup melted butter. Stir until well combined. Spread over cooled crust. Bake 30-35 minutes or until cake is set 3 inches from edge but still wobbly in center when pan is gently shaken.
Cool at room temperature 30 minutes. Refrigerate 1 hour or until completely cooled. Carefully release and remove side of pan.
In small microwave-safe bowl, microwave chocolate chips on HIGH until melted and smooth, about 30-45 seconds. Transfer chocolate to a resealable bag with a tiny hole cut in one corner. Pipe spider web design on top. Store in refrigerator, covered.