Lightly grease a 3-quart rectangular baking dish. Arrange bread slices in baking dish.
In a large bowl, stir together eggs, milk, granulated sugar, and vanilla. Slowly pour over bread. Press lightly with the back of a large spoon to moisten bread. Cover and chill in the refrigerator for 8 to 24 hours.
Combine flour, brown sugar, and cinnamon. Using a pastry blender, cut in butter until pieces are the size of small peas. Cover; chill in refrigerator for up to 24 hours. Before baking, sprinkle blueberries over bread; sprinkle flour mixture over berries. Bake, uncovered, in a 350 degree F oven 25 to 30 minutes or until a knife inserted off-center comes out clean. Let stand 5 minutes; top with strawberries and whipped topping, if desired. Cut into squares. Makes 8 servings.