Heat your oven to 375°F. Grease a 9x9 baking dish.
Cut brioche buns into eighths and spread them throughout the baking dish. Place berries evenly throughout the brioche pieces.
Begin making custard. Take a medium mixing bowl and combine milk, cream, eggs, sugar, and vanilla. Whisk until smooth.
Pour custard over berries and brioche pieces, making sure everything is evenly coated. Allow this mixture to sit for 15 minutes to allow for absorption.
Bake for 30-35 minutes or until golden brown.
Allow to cool for 10 minutes and then top with powdered sugar. Enjoy!