Here is one from THE BEST OF BEYERLY'S, A Recipe Collection. Byerly's is an upscale grocery in Minneapolis/St. Paul and they published this in a book for customers 21 years ago. I've made this recipe a few times and like it the best.
"1/2 cup butter or margarine
1/2 cup minced onions
2/3 cup flour
1 teaspoon dry mustard
1 teaspoon paprika
1/8 teaspoon cayenne pepper
1 teaspoon salt
1 (10-3/4 ounce) can chicken broth
4 cups milk
1 (12 ounce) can beer [please use bottle of ale]
3 cups finely shredded sharp Cheddar cheese (12 ounces)
Melt butter in large kettle; saute onion until soft. Blend in flour and seasonings; gradually stir in broth, milk and beer. Cook over medium heat, stirring constantly until mixture comes to a boil; boil and stir 1 minute. Stir in cheese; heat and stir until smooth.
Ladle into soup cups or bowls. Garnish with popcorn."
I tend to add a little more onion, use nothing but premium hoppy ale like an IPA that will come through on the taste rather than the BudMillerCoors bland lagers, and go a little thicker with the cheese. If you want super rich substitute some half and half for some of the milk or use whole milk. Since you are going to go into cardiac arrest eating this concoction you might as well enjoy it fully and use the butter instead of the margarine.