Preheat oven to 350 F and line a metal or glass cake pan with parchment.
Dice the peppers, onions, and ham.
In a skillet over medium-low heat, add the butter. Once it’s melted, saute the peppers and onions until no longer crisp, and slightly softened. Season with half the salt, stir, and set aside.
Back in the skillet, melt the bacon grease and fry the ham just until lightly browned on both sides.
Add the vegetables back into the pan and combine well, turn off the heat.
While vegetables & ham are cooking, slice and cube the bread and set aside.
In a medium-sized bowl, beat the eggs + egg whites together with the milk or cream, the seasonings, and the remaining salt.
Layer the cubed bread, then the ham & peppers mixture, and then sprinkle on half the grated cheese. Pour the egg mixture over all, coating everything evenly.
If you notice the bread-to-liquid ratio is too high, add more liquids (3-4 more beaten eggs mixed with milk). You’re better off with a more soupy batter than a very thick one.
Cover the baking pan tightly with foil and bake 40-45 minutes until the center is no longer jiggling/wet, and uncover. Then sprinkle on the remaining cheese and let bake for 15-20 more minutes or until the cheese is golden on top.
Let cool about 5-10 minutes before slicing and serving.
Makes 6 to 8 servings. Refrigerate leftovers up to 5 days.