Slice French bread loaf in half and place in a baking dish
Whisk together 4 eggs, 2 ¼ cup whole milk, 3 tablespoons granulated sugar, 1 teaspoon vanilla extract, ½ teaspoon ground cinnamon, and ¼ teaspoon kosher salt
Pour egg mixture over sliced French loaf and let bread soak up the liquid
Cover and refrigerate overnight or for several hours
Make streusel topping by combining ½ cup all-purpose flour, ⅓ cup brown sugar, ½ teaspoon ground cinnamon, ½ teaspoon kosher salt, and ¼ cup cold unsalted butter until crumbly
Spread streusel topping over the bread mixture
Top with 10 oz frozen blueberries
Bake at 350°F for 40 minutes
Slice and serve, optionally topped with powdered sugar
