1. To make Cake: Preheat oven to 350°F. Grease and flour 9- x 5-inch loaf pan.
2. Sift together 1 cup plus 3 Tbs. flour, cornmeal, baking powder, and salt in bowl. Beat brown sugar; oil; Cointreau, if using; and vanilla in separate bowl with electric mixer until smooth. Beat in eggs. Alternately add flour mixture and yogurt to egg mixture until combined.
3. Toss blueberries with remaining 1 Tbs. flour, and fold into batter. Pour into prepared pan, and bake 70 minutes, or until toothpick inserted in center comes out clean. Cool 10 minutes.
4. To make Glaze: Whisk together all ingredients in small bowl. If not using Cointreau, add 1 Tbs. water.
5. Unmold Cake, and poke top all over with wooden skewer. Brush Cake with Glaze. Cool completely before serving.