Preheat oven to 325 degrees F. In a large bowl, combine graham cracker crumbs, sugar and butter. Press evenly into bottom and halfway up the side of a 9-inch springform pan. Bake for 6-8 minutes; set aside to cool.
In a small saucepan over medium heat, melt 6 tablespoons butter. Add 1/2 cup light brown sugar and cook, stirring occasionally, until starting to bubble and sugar is dissolved, about 2 minutes. Remove from heat and stir in dark corn syrup, 1 1/2 cup chopped pecans, eggs, vanilla extract and salt. Pour into prepared crust; set aside.
In a stand mixer with paddle attachment, beat cream cheese, 1 cup light brown sugar and flour until fluffy. Add eggs, one at a time, beating after each addition until just combined. Add 1 cup heavy cream and stir until well combined. Pour over pecan pie filling and place springform pan on a baking sheet. Bake for 60-70 minutes until cake jiggles slightly when moved or toothpick inserted in the center comes out clean. Turn off oven and leave cake in for 1 hour, then remove from oven and let cool completely.
To Make the Pecan Topping: Melt butter in a small saucepan over medium heat. Add brown sugar and cook until bubbling, about 3-5 minutes. Remove from heat and stir in 1 1/2 cups toasted pecans, 1/3 cup heavy cream and pinch of salt. Let cool to room temperature then spoon over. Cooled cheesecake. Slice to serve or store refrigerated.
