Together in small bowl, combine 1/4 cup sugar and brown sugar, cut in butter until crumbly. Stir in oats. Reserve 1 cup for topping.
Press remaining crumb mixture into bottom of 13x9 inch baking pan, prepared with non-stick spray or coating
Bake 15 minutes.
Over medium heat in small sauce pan, combine chocolate and evaporated milk. Stir in 1/4 cup sugar and stir until melted, reducing heat to low until ready to use.
In medium sized mixing bowl, combine cream cheese, spices, and remaining 1/2 cup sugar, beat until smooth. Add pumpkin, vanilla, and eggs, beat on low speed until just blended.
Pour chocolate mixture over warm crust, using back of spoon to evenly distribute.
Evenly sprinkle Craisins over chocolate layer.
Pour pumpkin mixture over chocolate, sprinkle with reserved crumb mixture.
Bake 25 minutes, until center is set. Cool on wire rack.
Serve upon cooling, or refrigerate for later consumption.