1For best results, coat the inside of the Bundt pan with cooking spray just before filling it with the batter to prevent it from pooling in the bottom.
1. Preheat oven to 350 degrees. In a bowl, whisk 2 1/2 cups flour with baking powder and salt; set aside.
2. In a mixing bowl, cream butter and sugars on high speed until light and fluffy. Add eggs, one at a time, beating until incorporated. Beat in vanilla. Reduce speed to low; add flour mixture in three additions, alternating with two additions of sour cream.
3. In a bowl, toss blueberries and zest with remaining teaspoon flour; gently fold into batter. Coat a 12-cup nonstick Bundt pan with cooking spray. Spread batter in prepared pan.
4. Bake cake on bottom rack of oven until a toothpick inserted into center of cake comes out clean, 60 to 70 minutes. Cool in pan 20 minutes. Invert onto a rack; cool completely, top side up. Dust with confectioners' sugar before serving, if desired.