Preheat the oven to 325°F (163°C) and grease a 9-inch springform pan.
Combine graham cracker crumbs, sugar, and melted butter until evenly moistened.
Press the mixture firmly into the bottom of the springform pan.
Bake the crust for 8–10 minutes, then let it cool slightly.
Beat the softened cream cheese and sugar until smooth and creamy.
Add the eggs one at a time, mixing just until incorporated.
Mix in vanilla, sour cream, flour, and salt until smooth.
Pour the cheesecake filling over the prepared crust and smooth the top.
Bake for 45–50 minutes, until the edges are set and the center still has a slight jiggle.
Remove the cheesecake from the oven and let it cool for about 15 minutes.
Combine pecans, brown sugar, maple syrup, melted butter, eggs, vanilla, cinnamon, and salt in a bowl.
Carefully spoon the pecan mixture evenly over the cheesecake.
Return the cheesecake to the oven and bake for another 20–25 minutes, until the pecan topping is set.
Cool completely at room temperature, then refrigerate for at least 5 hours or overnight.
Carefully remove the springform pan, slice, and serve chilled or slightly softened.