In a large skillet, heat butter and oil over medium heat. Add onion and peppers. Cook and stir until crisp-tender. Add garlic; cook 1 minute longer. Stir in hash browns, salt, pepper and, if desired, pepper sauce., Transfer to a 5-qt. slow cooker coated with cooking spray. Cook, covered, 3-4 hours or until heated through. Sprinkle with parsley just before serving.