Peel sweet potatoes and parsnips; cut into sticks about 1/2 inch by 3 to 4 inches. Lightly coat a 12- by 17-inch rimmed baking pan with cooking oil spray.
Place vegetables in pan, cover tightly with foil, and bake in a 400 regular or convection oven until just tender when pierced, 35 to 40 minutes.
Meanwhile, in a small bowl, combine maple syrup, brown sugar, bourbon, butter, orange peel and juice, and cardamom.
Increase oven temperature to 45
Remove foil from pan and sprinkle pecans over vegetables.
Pour the syrup mixture over vegetables and pecans; turn pieces with a spatula to coat evenly.
Bake until syrup mixture thickens and sticks to vegetables, 25 to 35 minutes longer, turning pieces often to prevent scorching.
Transfer candied vegetables to a serving dish. Season to taste with salt.