Line a 13 x 9 inch pan with foil and spray lightly with nonstick cooking spray; set aside.
To make the pumpkin layer:
Combine sugars, milk, butter, pumpkin puree and spice in a large sauce pan over medium heat. Cook, stirring constantly, until mixture boils. Once boiling, stir constantly until mixture reaches 240 degrees, about 10 to 12 minutes. Remove pan from heat and quickly stir in white chocolate chips and marshmallow crème until melted and smooth. Spread pumpkin fudge into foil pan and let set.
To make the chocolate layer:
Combine sugar, butter, evaporated milk and marshmallow creme in a large saucepan over medium heat. Stir constantly until mixture boils. Once boiling, stir for another 5 minutes. Remove from heat and stir in vanilla and chocolate chips until melted and smooth. Pour chocolate mixture over pumpkin layer. Spread chopped pecans over top of chocolate and press down lightly with the back of a spoon to set in chocolate. Refrigerate for at least 6 hours, or overnight. Remove fudge from pan, remove foil and cut into 1 inch pieces.