Preheat the oven to 300 degrees F (150 degrees C).

Whisk flour, pumpkin pie spice, and baking soda together in a medium bowl until well combined. Set aside.

Beat brown sugar and butter together in a large bowl with an electric mixer until smooth and creamy; beat in pumpkin purée until incorporated. Beat in eggs and vanilla, then beat in flour mixture until just combined. Stir in white chocolate chips and pecans until evenly distributed.

Drop rounded tablespoons of dough 2 inches apart on an ungreased cookie sheet.

Bake in the preheated oven until edges are set, 20 to 22 minutes.