Preheat your oven to 204 °C (200 °C) and line a small baking sheet with parchment paper for easy cleanup.

In a small mixing bowl, vigorously whisk together the Greek yogurt, egg, maple syrup, and vanilla extract until the mixture is completely smooth and free of lumps.

Place the bread slices on the prepared baking sheet. Use the back of a spoon to press down the center of each slice, creating a shallow well while keeping the edges intact.

Divide the prepared custard mixture evenly between the two bread slices, pouring it directly into the compressed wells. Top with the fresh berries.

Bake in the preheated oven for 10 to 12 minutes, or until the custard is set and the edges of the bread are beautifully golden brown and crisp.

Remove from the oven, let cool for 2 minutes, then dust with powdered sugar if desired before serving warm.