Preheat oven to 375˚F. Line muffin pan with paper liners, or lightly spray a muffin pan.
In a medium bowl, combine the flours, baking powder, baking soda, salt, 1 teaspoon cinnamon and nutmeg.
In a large bowl, cream together the 1/2 cup butter, 1/2 cup brown and white sugar until light and fluffy. Add the eggs and vanilla and beat well. Slowly add the flour mixture, mixing until fully incorporated. Fold in the pears.
Spoon the batter into the prepared muffin pans.
In a small bowl, combine the streusel topping ingredients together. Sprinkle over the muffins.
Bake for around 15 minutes, or until a toothpick inserted comes out clean. Place on wire racks to cool completely.