Spray an 8x8 baking dish with cooking spray, add a piece of parchment paper cut to fit the pan, if desired, and spray again. Be sure to coat the pan well so it doesn’t stick! Set aside.
Cut bread into 1” cubes, set aside.
In a medium sized bowl combine eggs, milk, ¼ cup of brown sugar, 1 tsp vanilla extract, and ½ tsp cinnamon. Whisk together well and set aside.
In a second medium sized bowl combine remaining ½ cup brown sugar, flour, walnuts, cranberries, remaining 1 tsp cinnamon, ¼ tsp salt and melted butter. Combine well, it’ll turn into a crumbly mixture. Set aside.
Now add ½ of your bread cubes to your prepared pan to cover the entire bottom. Then add ½ of your cranberry walnut mixture on top, followed by remaining bread cubes over that.
Pour your egg mixture over top of the bread cubes aiming to evenly disperse it throughout the pan and get all pieces wet.
Add remaining ½ of cranberry walnut mixture on top and gently press down to get it to settle into the bread pieces.
Cover your brioche french toast bake with aluminum foil and refrigerate for at least 1 hour and up to overnight.
When ready to bake, preheat the oven to 350 degrees and bake covered for 20 minutes and then remove the aluminum foil and bake uncovered for an additional 30 minutes.
Remove from the oven and let it cool slightly for 5-10 minutes before serving. Top with a dust of powdered sugar and a drizzle of maple syrup and enjoy!