01 - Preheat oven to 375°F and line a baking sheet with parchment paper.
02 - Place bread slices on the prepared baking sheet. Using the back of a spoon, press into the center of each slice to form a shallow well, keeping edges intact.
03 - In a mixing bowl, thoroughly whisk egg, Greek yogurt, honey or maple syrup, vanilla extract, and a pinch of salt until a smooth, creamy custard forms.
04 - Spoon the custard mixture evenly into the wells of the bread slices.
05 - Scatter fresh mixed berries evenly over the custard-filled bread.
06 - Bake for 12 minutes or until the custard is just set and the bread edges are golden brown.
07 - Remove from oven, dust lightly with powdered sugar if desired, and serve warm.