Cut 1 (8 ounce) loaf French bread diagonally into eight 1 1/2-inch thick slices. Cut a 2-inch-long slit 1 inch deep in top of each slice to form a pocket. Divide 1 cup fresh blueberries into 8 portions; fill pockets with berries.
Whisk together 2 cups milk, 3 large eggs, 1/4 cup sugar and 1/4 teaspoon vanilla extract in large bowl. Combine 1/4 cup sugar and 1/4 teaspoon cinnamon in cup. Set both aside.
Soak bread slices in egg mixture 30 seconds to 1 minute.
Meanwhile, melt 1 tablespoon butter or margarine in large nonstick skillet over medium heat. Cook 4 bread slices until golden, turning once, 4 to 5 minutes. Transfer to platter; cover and keep warm. Wipe skillet. Repeat process with another 1 tablespoon butter and remaining bread. Transfer French roast to 4 serving plates; sprinkle tops with cinnamon-sugar. Serve with maple syrup, if desired.