Using a paring knife, trim any discolored leaves from the Brussels sprouts. In a large pot, bring 2 quarts of salted water to a rolling boil. Add Brussels sprouts, return to a boil and cook 5 minutes. Drain immediately in a colander 5–7 minutes. Transfer to a 9"x11" casserole dish and set aside. Preheat oven to 375°F. In a 1-gallon saucepot, cook bacon over medium-high heat until lightly browned and fat is rendered. Be careful not to brown or burn the bacon fat. Using a slotted spoon, remove the bacon and sprinkle over the Brussels sprouts. Return the saucepot with bacon fat to medium-high heat then add onions, celery, bell peppers and minced garlic. Sauté 3–5 minutes or until vegetables are wilted. Add flour and stir constantly to create a white roux. When flour is well blended, add half and half and chicken broth. Using a wire whisk, stir until a thickened white sauce is achieved. Add Creole mustard and Parmesan cheese, blending well into the sauce. Season to taste using salt, black pepper and granulated garlic. Spoon the sauce evenly over the Brussels sprouts and top with Cheddar cheese. Sprinkle lightly with paprika and bake on center rack of oven 30 minutes or until cheese is bubbly and golden brown. Cool 10 minutes before serving.