Bring a large pot of lightly salted water to boiling. Add sweet potatoes and boil 12 minutes, until tender. Drain and return to pot.
Meanwhile, in a small skillet, melt butter over medium heat. Stir in maple syrup, pumpkin pie spice and salt. Cook for 1 minute; stir until sauce is smooth.
Add butter mixture to pot and mash to desired consistency. Transfer sweet potatoes to a serving dish. Sprinkle top evenly with chopped pecans. Makes 8 servings.