Blueberry Ripple Cake

3/4 cup flour
3/4 cup packed brown sugar
1 1/4 teaspoons cinnamon
1/4 teaspoon salt
1/3 cup cold butter
1/2 cup chopped pecans
1 (18.25 ounce) box white cake mix
1 1/4 cups fresh or frozen blueberries

Combine the flour, brown sugar, cinnamon and salt. Cut in the butter until crumbly. Stir in pecans. Sprinkle half into greased 9 x 13-inch pan.

Prepare cake mix according to package directions. Spread batter over the pecan mixture. Top with blueberries and remaining pecan mixture. Swirl with a knife. Bake a 350 degrees F for 45-50 minutes.