Onion Cheese Soup
["3 Spanish onions", "4 Tbsp. butter", "4 Tbsp. flour", "2 c. milk", "2 c. chicken stock", "1/2 tsp. salt", "1/2 tsp. pepper", "1 egg yolk, beaten", "1 c. mild Cheddar cheese, grated"]
["Melt butter in 4-quart saucepan over low heat.", "Add onions and saute until lightly browned.", "Add flour and cook an additional 5 minutes until butter and flour are well blended.", "Slowly add milk and chicken stock, stirring constantly to prevent lumps.", "Season with salt and pepper, continuing to stir until soup thickens. Whisk in egg yolk slowly and add cheese.", "Simmer for another 5 to 10 minutes, stirring to prevent burning.", "Remove from heat and serve immediately."]
["onions", "butter", "flour", "milk", "chicken stock", "salt", "pepper", "egg yolk", "Cheddar cheese"]