In a heavy saucepan, combine the first 6 ingredients (butter, sugar, brown sugar, evaporated milk, pumpkin, pumpkin pie spice); cook mixture over medium heat.

Bring mixture begins to a boil, stirring constantly. Boil mixture until candy thermometer reaches soft-ball stage (234-243 degrees). It's best to use a candy thermometer but if you don't have one you can boil the mixture until it gets foamy and once it's foamy boil for an additional 4-6 minutes.

Remove pan from heat; stir in chocolate chips until melted. It's important to remove it from the heat so that the chips don't get overheated and turn grainy.

Add the marshmallow cream, pecans, and vanilla and stir to combine well.

Pour into a buttered 13x9 inch baking pan; cool to room temperature.

Cut into squares; store in the refrigerator in an air-tight container. I like eating it at room temperature.