1Preheat oven to 375 F.
2Pierce sweet potatoes all over with a fork. Microwave on high for 15 minutes or until completely cooked through.
3Let rest 5 minutes or until cool enough to handle.
4Topping: Meanwhile, combine the pecans, flour, sugars, cinnamon and 1/4 teaspoon salt. Stir to blend. Mix in 1/4 cup butter. The topping should form sandy clumps. Refrigerate.
5Split the potatoes in half lengthwise and scoop out some of the flesh inside.
6Arrange the sweet potato "halves" on a baking sheet. In a medium bowl, combine the sweet potato flesh with the remaining 1/4 cup butter, orange zest and 1/2 teaspoon salt.
7Spoon the filling back into each potato half and top with the topping on a baking tray. Place the tray in the center of the oven and bake until the topping browns, 15 to 20 minutes.