Preheat oven to 350°F
Butter and flour 9" x 13" inch baking pan - set aside
Chop and toast walnuts, set aside
Sift together flour, cinnamon, baking soda, nutmeg, and salt in a medium-size bowl
Using an electric mixer beat together brown sugar, oil, eggs, sugar, water, and vanilla in a large bowl until it is very smooth
Add in the dry ingredients. Mix well.
Core pears and cut into 1/2 inch cube unpeeled pieces
Hand stir in pears and walnuts - batter will be lumpy
Pour batter into prepared baking pan. Bake until the top is medium brown and a toothpick comes out clean, about 55 minutes.
Cool completely and cut into squares.Serve with vanilla ice cream or whipped cream.