Spray an 8-inch round or square baking pan with cooking spray.
Line the bottom of the pan with the sliced strawberries, making sure it's covered completely.
Top the pan with the slices of bread, breaking them up as needed, so that they're packed in on top of the strawberries.
In a mixing bowl, combine the beaten eggs, milk, 6 tablespoons of PB2 powder, and vanilla. Whisk well to combine.
Pour the egg mixture evenly over the bread and gently tap the pan on the counter to help the eggs mixture settle in evenly over the bread. Lay a piece of plastic wrap or foil over the top, and weight it with a plate, pot or something slightly heavy. This will help the bread soak up the liquid.
Place the pan in the refrigerator for at least 30 minutes, or overnight.
When ready to bake, preheat the oven to 325°F and place the oven rack in the middle position.
Bake the French toast for 45 minutes or until it's puffy, golden, and a knife inserted in the center comes out clean. Remove it from the oven and let it cool for at least 15 minutes.
Serve as is, with the fruit on the bottom, or run a knife around the outside edge, and then invert the pan over a large plate. Give it a few gentle shakes and it should pop out easily.
To make the optional Strawberry Peanut Butter Sauce
While the French toast is baking, combine the thawed strawberries and maple syrup in a saucepan over medium-high heat. Bring the mixture to a simmer and let it cook for about 10 minutes, or until the strawberries are softened and broken down. Remove from the heat.
Let the strawberries cool for about 15 minutes, and then place the mixture in a blender, along with 1 tablespoon (or more or less to taste) of PB2 powder. Blend until smooth. Serve over the french toast slices.
Note: nutrition facts is without the strawberry peanut butter sauce.