In a large skillet heat oil over medium heat. Add the sausage, stir frequently. After five minutes add the onion and red pepper. Continue cooking until sausage is browned and crumbly. Drain if needed.
Combine the sausage mixture with the bread, red pepper and cheese (reserve approximately 1/3 cup cheese for the top).
Arrange the sausage/bread/cheese mixture evenly in a buttered, 13 x 9-inch baking dish.
In a large bowl, whisk together eggs, milk, mustard, salt, pepper and hot sauce
Carefully pour egg mixture over the ingredients in the baking dish.
Allow the dish to rest for one-hour. The casserole can be prepared, up to this point, a day in advance. It must be covered and refrigerated.
When ready to bake, remove from the refrigerator and let stand 30-minutes prior to baking.
Preheat the oven to 350° F
Bake casserole until set and golden, about 40 – 45 minutes. A knife inserted in the middle should come out clean.
Top with the remaining cheese.
Let stand for 10 minutes before serving. Garnish with fresh chives. Serves 8.