Spray the insert of a 6-quart slow cooker with cooking spray.

Gently combine the pumpkin puree, granulated sugar, pumpkin pie spice and salt (And optional vanilla) in a large bowl, then dump it into the slow cooker insert. Spread out evenly.

Sprinkle the DRY cake mix evenly over the pumpkin puree, then, as evenly as possible, pour the melted butter on top and finish by sprinkling with the chopped pecans.

Cover and cook on low for 4 to 4.5 hours. Do NOT remove the cover in this time. Just trust it's doing its thing. The edges of the cake should be starting to brown and crisp slightly when done.

When ready to serve, use a handheld or stand mixer woth a whick attachment to whip the cream and powdered sugar (and optional vanilla) together in a large bowl until stiff peaks form. Or make ahead too and store covered in fridge until serving time.

Serve the cake warm with a dollop of the whipped cream.

NOTE: You could also use chopped walnuts instead of pecans, or simply omit nuts if there is an allergy or you do not like them. But they are a great textural element, adding an excellent crunch.

NOTE: If the cake is done before it's time for dessert it is perfectly fine to switch to warm until you're ready.