Pre-heat oven to 350 degrees. Coat a 9-x13-inch baking pan with nonstick cooking spray. Set aside.

For cake, combine cake mix, sour cream, eggs, vegetable oil, and lemon zest in a large bowl. Beat on low speed for 30 seconds, then on medium-high for 2 minutes. Fold in the 1-1/2 cups cranberries. Pour batter into prepared baking pan. Bake at 350 degrees for 30 minutes. For topping, in a medium-size bowl whisk together the flour, brown sugar, cinnamon, nutmeg, and salt. Stir in butter until mixture is moistened and starts to clump together. Carefully remove cake from oven. Sprinkle crumb mixture evenly over the top. Scatter with remaining cranberries. Return cake to oven and bake at 350 degrees for an additional 20 minutes. Remove pan to wire rack and cool completely. Dust lightly with confectioners sugar and cut into 16 squares. Makes 16 servings.