3 tablespoons butter or margarine
3 tablespoons all-purpose flour
2 (14 1/2-ounce) cans chicken broth
2 cups coarsely chopped broccoli
3/4 cup chopped carrots
1/2 cup chopped celery
1 small onion, chopped
1/2 teaspoon salt
1/4 teaspoon garlic powder
1/4 teaspoon dried thyme
1 egg yolk
1 cup heavy cream
1-1/2 cups (6 ounces) shredded Swiss cheese
Melt butter in a heavy 4-qt. saucepan; add flour. Cook and stir until thick and bubbly; remove from the heat. Gradually blend in broth. Add next seven ingredients; return to the heat and bring to a boil. Reduce heat; cover and simmer for 20 minutes or until vegetables are tender. In a small bowl, blend egg yolk and cream. Gradually blend in several tablespoonfuls of hot soup; return all to saucepan, stirring until slightly thickened. Simmer for another 15-20 minutes. Stir in cheese and heat over medium until melted.