In a large mixing bowl, combine the softened butter, flour, sugar, brown sugar, and cinnamon together with a pastry blender.
Cut the pears in half, and scoop the center of each pear out with a melon baller, being sure to scoop out all the seeds. Place all the halves on a baking sheet.
Fill in each center with the crumb topping. Then sprinkle more on top, covering each pear with the topping.
Sprinkle with chopped pecans, if desired.
Bake at 375° F for about 45 minutes, or until the crumbled topping is golden and the pear is tender when poked with a fork.
To serve, top with whipped topping or vanilla ice cream, if desired, and serve while warm.