Preheat oven to 325°F. Wrap the outside of a 9-inch springform pan tightly with 2-3 layers of heavy-duty foil to prevent water bath leaks.
Mix graham cracker crumbs and 1/4 cup sugar in a bowl. Stir in melted butter until mixture resembles wet sand. Press firmly into the bottom and about 1/2 inch up the sides of the prepared pan.
Bake the crust for 10 minutes. Remove and set on a wire rack to cool while making the filling. Keep the oven on at 325°F.
Beat softened cream cheese and 1 cup sugar on medium speed until smooth, about 2-3 minutes. Add sour cream, flour, vanilla, and salt, mixing on low until combined.
Add eggs one at a time, beating on low just until incorporated. Do not overmix. Pour filling over cooled crust and smooth the top with a spatula.
Place the foil-wrapped springform pan in a large roasting pan. Carefully pour hot water into the roasting pan until it reaches halfway up the sides of the springform pan.
Bake for 60-70 minutes until edges are set but the center jiggles slightly. Turn off oven, crack the door, and let cheesecake sit inside for 1 hour.
Remove cheesecake from water bath and foil. Cool completely on a wire rack, about 1 hour. Cover and refrigerate for at least 6 hours or overnight.
In a medium saucepan over medium heat, melt butter with brown sugar, stirring until smooth. Whisk in corn syrup and heavy cream. Bring to a gentle simmer for 2-3 minutes until slightly thickened.
Remove from heat and stir in chopped pecans, vanilla, and salt. Let cool for 15 minutes until thick but still pourable.
Release the springform pan and place the chilled cheesecake on a serving plate. Pour the pecan topping evenly over the top, letting it spill slightly over the edges.
Refrigerate for 15-20 minutes to set the topping. Slice with a sharp knife, wiping the blade clean between cuts for neat slices.