01 - Preheat the oven to 350°F. Line a 12-cup muffin tin with paper liners or lightly grease each cup with cooking spray.
02 - In a large bowl, whisk together the eggs, milk, protein powder, maple syrup, cinnamon, vanilla extract, and salt until completely smooth and well combined.
03 - Add the bread cubes to the egg mixture, folding gently until all pieces are evenly coated. Allow the mixture to rest for 5 minutes so the bread absorbs most of the liquid.
04 - Divide the soaked bread mixture evenly among the 12 muffin cups, pressing down lightly with a spoon to compact each portion.
05 - Sprinkle your choice of toppings (nuts, chocolate chips, or berries) over each muffin, pressing them gently into the surface.
06 - Bake for 20 to 25 minutes, or until the muffins are puffed, golden brown on top, and set firmly in the center.
07 - Let the muffins cool in the tin for 5 minutes before transferring to a wire rack. Serve warm with maple syrup or Greek yogurt, or allow to cool completely for storage.