Preheat the oven to 350°F and grease your muffin pan.
In a large bowl add in 6 eggs, 3/4 cup milk, 1/2 cup maple syrup, 1 tsp cinnamon, 1 tsp vanilla extract, 1 cup unflavored protein powder and whisk until well combined.
Fold in your 5 cup bread cubes gently, as well as the berries if you're using them.
Using a spoon, fill up your muffin pan with the mixture.
Prepare the crumble topping by mixing 1/4 cup coconut sugar, 1/4 cup butter and 1/3 cup all-purpose flour in a small mixing bowl.
Pour the crumble mixture on top of the french toast muffin cups - bake for 15-20 minutes at 350°F, or until golden brown on top.