Cut the bread into 1" cubes and arrange on a baking sheet. Toast in a 300 degree oven for 25-30 minutes, until browned and crisp.
Preheat the oven to 350 degrees.
Add the toasted bread cubes and crumbled cornbread to a large bowl and mix GENTLY to combine. Heat a skillet over medium high heat and brown the andouille sausage. Set the sausage aside.
Heat the butter in a skillet over medium heat and add the onions, garlic and red pepper and cook until they are softened, 2-3 minutes. Add the andouille sausage and cook for 1-2 minutes. Add the tomatoes and seasoning and cook for 1-2 minutes. Add the shrimp and cook until they turn pink.
Remove from heat and toss with the bread mixture. Slowly add chicken broth until the stuffing is dampened, but not too wet. You may or may not need to the full 1-2 cups of broth. Mix GENTLY so as not to break up the bread cubes.
Pour the mixture into a greased baking dish and bake, covered, for 45 minutes. Remove the cover and bake an additional 15 minutes, until browned and slightly crisp on top.
It is important to toast the bread cubes instead of using stale bread cubes. Stale bread cubes will soak up too much liquid and you'll end up with soggy stuffing.
I use a cornbread/white bread combo. For the white bread, I recommend French bread cut in 1 inch cubes. The larger pieces of bread add great texture to the stuffing, so it doesn't become a pile of mush.
When mixing the sausage mixture in with the bread cubes, be careful to toss gently. Over-mixing will break down the bread cubes and you'll end up with mushy stuffing.
We initially bake it covered to prevent the stuffing from drying out. Removing the cover for the last 15-20 minutes allows the bread cubes to toast slightly for a chewy browned texture on top (which is amazing by the way).
To make ahead of time, you can prepare the stuffing in the baking dish and refrigerate overnight. Bake it the next day according to these instructions.
Stuffing can be frozen before or after baking it. Be sure to use an airtight container, or wrap in freezer safe plastic wrap, then again in foil. If it's frozen before baking, let it thaw out in the fridge, then bake according to the instructions above. If it is already baked, thaw it in the fridge and bake at 350 degrees until it is warmed through, about 15-20 minutes.