Preheat oven to 400 degrees. Using a fork or knife, pierce sweet potatoes several times then place in oven to roast for about 45 minutes or until tender.
While sweet potatoes roast, make pie crust. Start the crust by incorporating sea salt, flour, and butter until a coarse meal forms. This can be done in a bowl by hand by hand or in a food processor. Add cold water and continue working or pulsing mixture until a dough forms. Shape dough into a disc (like a hockey puck), wrap in plastic, and chill for at least 30 minutes.
Once sweet potatoes are roasted, carefully remove from oven and place in fridge to cool to room temperature. Reduce oven heat to 375 degrees.
Remove pie crust dough from fridge and roll out into about ¼-inch thickness. Place dough into a 9-inch pie pan and fold or crimp edges, as desired. Place a sheet of parchment paper over crust then cover with pie weights or dry goods. Transfer pan into oven to par bake for about 10 minutes then remove and reduce oven heat to 350 degrees.
While crust par bakes, make sweet potato filling. Remove skin from roasted sweet potatoes and combine with heavy cream, butter, egg, brown sugar, granulated sugar, whiskey, nutmeg, cinnamon, and sea salt. This step can be done with a mixer, by hand, or in a food processor. I recommend using a food processor for the smoothest filling. The result should be thick, custard-like, and free of lumps. If filling is too thin, place in the fridge to stiffen up a bit before assembling pie.
In another bowl, mix together the corn syrup, brown sugar, eggs, butter, vanilla, and cinnamon until smooth and uniform. Stir in pecans.
To assemble pie, spread sweet potato filling into prepared crust. There should be about one inch of space between the top of the sweet potato filling and the edges of the pie crust. Next, gently pour pecan pie filling over top. This layer should be almost flush with the top of the pie pan.
Transfer pie to oven and bake pie for about one hour or until filling is set, placing a sheet pan on the rack below the pie to catch any drips. The top of pie will puff up as it bakes but will settle as it cools. Cool pie completely before cutting.