Preheat oven to 300 degrees F. Lightly coat a 9x13 inch casserole dish with non-stick spray, set aside.
Line the bread cubes in a single layer on a large baking sheet(s) and bake for 10 minutes. Remove from oven and let cool. Place the bread cubes in a large mixing bowl, set aside.
Increase oven's heat to 350 degrees F.
In a large skillet cook the chorizo sausage, breaking up with a spoon to crumble. Once fully cooked remove from pan to a paper towel lined plate. Wipe out skillet and return it to the stove.
Add the butter to the skillet over medium heat. Once it's melted toss in the onions and brussel sprouts, stirring occasionally, until the vegetables are soft and tender (about 5 to 7 minutes).
In a small bowl whisk together the eggs, broth, and seasonings. Combine the sautéed veggies with the bread cubes, add in the chorizo sausage, broth mixture and cranberries. Gently stir until the mixture is evenly coated. Transfer to the prepared casserole dish.
Bake for 30 to 35 minutes, or until the top is a light golden brown. Enjoy!