Microwave squash on HIGH 2 minutes to soften. Cut in half. Peel squash; remove and discard seeds. Cut squash into 1" squares.
Cook squash in water in a large Dutch oven 30 minutes or until tender; drain.
Combine squash, 3 tablespoons butter, 3 tablespoons syrup, maple flavoring, and 3/4 teaspoon salt in a large bowl; mash with a potato masher until smooth.
Cook pecans, remaining 2 tablespoons butter, remaining 1/4 cup maple syrup, and 1/2 teaspoon salt in a medium skillet over medium-low heat 7 minutes or until syrup caramelizes and pecans begin to brown; cool in a single layer on a plate.
Sprinkle pecans over squash. Serve warm.