To make the streusel, combine all the ingredients except the butter with a fork. Then working quickly add the butter in tablespoons and working with your fingers crumble it into the streusel until well combined. Set aside.

Butter and flour a bundt pan and preheat oven to 350F.

In a medium bowl, whisk together the flour, pumpkin pie spice, baking powder, baking soda and salt. Set aside.

In a large bowl of a standup mixer with a paddle attachment add the oil and sugars, and mix well. Add in the eggs, and mix again. Add in the pear puree and the vanilla, and mix. Add in half the flour mixture followed by the sour cream and the remaining flour mixture. Mix well with each addition. Fold in the chopped pears.

Sprinkle in half the streusel to the bottom of the prepared pan. Pour in half of the batter. Sprinkle in the other half of the streusel followed by the rest of the batter.

Bake for 60 -70 min. or until done and a cake tester comes out clean. Let rest for 15 min. and then invert onto a cooling rack to cool completely. Serve sprinkled with icing sugar if desired.