1. For crust, in a medium bowl whisk together flour,sugar,and salt. Using your fingers ( or a potato masher), quickly work cold, cubed butter into flour mixture (some butter pieces will be the size of oat flakes; some will be the size of peas). Create a well in mixture; pour in cold buttermilk. Using a fork, bring dough together. Try to moisten all the flour bits. Add a bit more buttermilk if necessary (you want mixture to be shaggy and moist but not outwardly wet).
on a lightly floured work surface dump out dough mixture. Gently knead into a disk. Wrap in plastic wrap; refrigerate for 1 hour.
On a well floured surface roll crust 1/2 inch thick and about 12 inches in diameter. Transfer to a pie pan. Trim edge almost even with the edge of pan. Fold edges under; crimp with fingers or a fork. Cover with plastic wrap; refrigerate at least 30 minutes and a max of 3 hours.
Place rack in center of oven; preheat to 425 degrees F.
for filling, in a medium saucepan cook pumpkin, sugars, spice and salt over medium heat until mixture begins to bubble. Cook 5 to 7 minutes, stirring frequently. (Mixture will become fragrant, and some of the water in the pumpkin will cook off.).
Remove from heat; transfer to a medium bowl. Stir in heavy cream. Stir in eggs and vanilla; whisk until thoroughly combined. Transfer mixture to prepared crust; bake 15 minutes. Reduce oven to 350 degrees F; cook 40-50 minutes more or until pie no longer jiggles in center.
Meanwhile, for pecan praline topping, in a medium saucepan combine brown sugar, butter, cream and salt over medium-low heat. Bring to a simmer; cook 3-5 minutes. Remove from heat; stir in vanilla, pecans, and cranberries, if desired. Let rest until pie comes out of oven.
Remove pie ; cool 30 minutes.
Check to see that praline topping is still pourable. If it has hardened too much, heat over low heat until pourable. Pour praline mixture over warm pie. Cool completely before serving.