01 - Preheat oven to 350°F (175°C). Grease a standard 12-cup muffin tin thoroughly with butter or nonstick spray.
02 - Evenly portion the cubed brioche or challah bread into each muffin cup, filling each approximately three-quarters full.
03 - In a large mixing bowl, whisk together eggs, whole milk, heavy cream, granulated sugar, vanilla extract, ground cinnamon, and salt until the mixture is smooth and homogenous.
04 - Carefully pour the custard mixture over the bread cubes, distributing liquid evenly among all muffin cups. Gently press the bread cubes down to ensure optimal absorption.
05 - Allow the filled muffin tin to rest at room temperature for 10 minutes to facilitate custard absorption.
06 - Top each portion with fresh berries if desired.
07 - Transfer to the oven and bake for 25 minutes, or until the tops are golden brown and the centers are set.
08 - Remove from the oven and allow to cool for 5 minutes. Gently release the French toast cups from the muffin tin.
09 - Serve warm, dusted with powdered sugar and drizzled with maple syrup to taste.