Heat oven to 350 degrees F. Coat 13 x 9 x 2-inch baking pan with nonstick cooking spray.
Drain canned pears, reserving about 2 tablespoons syrup. Cut pear slices crosswise in half.
In large bowl, combine cake mix, pudding mix, yogurt, eggs and oil. With mixer on low speed, beat 1 minute, scraping down sides of bowl, until blended. On high speed, beat 2 minutes. Fold in pears and raspberries.
Turn batter into prepared pan (distribute batter evenly, but do not flatten top as bumps of fruit and batter will create buckle). Sprinkle top with brown sugar, then walnuts.
Bake in 350 degree F oven 55 to 60 minutes or until toothpick comes out clean. Remove to wire rack; let cool.
In small bowl, stir together confectioners sugar and 2 teaspoons reserved pear syrup until smooth. Add additional pear syrup, 1/2 teaspoon at a time, to make pourable icing. Place icing in small plastic food-storage bag; snip off tiny end of one corner. Drizzle icing over cooled cake. Cut into squares. Makes 16 servings.