Heat 1 tablespoon butter and the oil in a large saucepan over medium-high heat. Add onion and garlic; cook, stirring frequently, until soft and translucent, 3 to 5 minutes. Sprinkle flour over the vegetables and cook for 1 minute. While stirring, slowly pour in chicken broth. Cook, stirring occasionally, until thickened, about 3 minutes. Stir in cream cheese, Worcestershire, pepper and salt, cook, stirring, until smooth, about 2 minutes. Remove from heat and stir in 1 1/2 cups cheese. Pour the cheese sauce over the broccoli.