In a medium saucepan, caramelize the sugar over medium-high heat until it is dark gold. Add pecans and stir to coat them. Add the butter and remove the pan from the heat. Stir the nuts until the butter is incorporated.
Spread the nuts evenly over the bottom of the piecrust. Set aside.
Preheat the oven to 425º.
In a large bowl whisk together the pumpkin, cream, and eggs until smooth. Add the remaining ingredients and whisk until smooth. Pour over the pecans.
Bake for 15 minutes at 425º. Lower the heat to 350º and continue to bake for 30–40 minutes until the custard is set, except for a nickel-size spot at the center of the pie.