Cream the butter; gradually add sugar, beating well at medium speed of an electric mixer. Add eggs, one at a time, beating well after each addition.
Combine the flour, baking powder, baking soda, and salt. Add to the creamed mixture alternately with the sour cream, beginning and ending with the flour mixture. Mix after each addition. Fold in apple and pear. Stir in vanilla.
Spread the batter in a greased 13 x 9 x 2 inch baking pan.
Combine 1 cup brown sugar, pecans, 2 tbsp butter, and cinnamon; sprinkle evenly over the batter.
Bake at 350 degrees for 45 to 50 minutes or until a wooden pick inserted in the center comes out clean.