Cut French bread diagonally into eight 1 1/2-inch thick slices.

Create a 2-inch-long, 1-inch deep slit in the top of each slice to form a pocket.

Divide fresh blueberries into 8 portions.

Fill each pocket with a portion of blueberries.

In a large bowl, whisk together milk, eggs, sugar, and vanilla extract.

In a separate cup, combine sugar and cinnamon.

Soak bread slices in the egg mixture for 30 seconds to 1 minute.

Melt butter or margarine in a large nonstick skillet over medium heat.

Cook 4 bread slices until golden, turning once, for 4 to 5 minutes.

Transfer cooked slices to a platter and cover to keep warm.

Wipe the skillet clean.

Repeat the process with the remaining butter and bread slices.

Transfer French toast to serving plates.

Sprinkle the tops with the cinnamon-sugar mixture.

Serve with maple syrup, if desired.