Preheat oven to 350°F.
To make the streusel, combine the flour, sugar, pecans, cinnamon, and salt in a 3 Qt. All-Clad Mixing Bowl. Cut the cold butter into very small pieces (about ¼ inch) and toss them in the mixing bowl to coat them with flour. Quickly work the mixture with your hands until it resembles coarse crumbs. Refrigerate the streusel until needed.
Peel the apples, then split them in half and scoop out the core. Cut the apples into roughly ¾ inch pieces and place them in a mixing bowl. Toss the apples with ¼ cup of flour to evenly coat all of the surfaces in flour.
To make the butterscotch, heat the All-Clad 3 Qt. Sauce Pot over low heat and melt the butter. Add the brown sugar and 4 tablespoons of the cream and slowly stir until smooth and homogenous. Raise the heat and bring the mixture to a boil and cook without stirring for 3 minutes. Remove the pan from the heat and let it sit for about half a minute. Stir in the remaining cream, salt, and vanilla extract.
Stir the apples and any remaining flour into the butterscotch and coat them evenly. Tap the sauce pot to help settle the apples into an even layer and dislodge air pockets. Use a rubber spatula to clean the sides of the sauce pan above the surface of the apples.
Now, quickly make the batter for the cobbler crust. In a small mixing bowl, combine the flour, sugar, baking powder, baking soda, and salt. Stir in the crème fraîche or sour cream until the mix just comes together to make a very thick batter. Do not over-mix.
Spoon the batter randomly over the top of the apples. It’s OK to leave some apples exposed on the surface; the batter will spread out as it bakes and form a uniform crust. Sprinkle the streusel on top of the batter, then place the sauce pot in the center of the oven and bake for 1 hour and 15 minutes.
Remove the pot from the oven and allow it to rest for about 15 minutes. Serve topped with vanilla ice cream.