Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
   1 1/2  pounds        raw shrimp in shells
     1/2  cup           butter
     1/4  cup           vegetable oil
   8      cloves        garlic -- finely
                        chop
   1                    dried de arbol chilies -- up to 3
                        -- coarsely crumbled
   1      tablespoon    fresh lime juice
     1/4  teaspoon      - salt
                        green onion tops -- slivered
                        for garnish

Preparation:

Preheat oven to 400F Shell and devein shrimp, leaving tails attached; rinse and drain well. Heat butter and oil in small skillet over medium heat until butter is melted and foamy. Add garlic, chilies, lime juice and salt. Cook and stir 1 minute. Remove from heat. Arrange shrimp in even layer in shallow 2-quart gratin pan or baking dish. Pour hot butter mixture over shrimp. Bake shrimp 10 to 12 minutes until shrimp turn opaque, stirring once. Do not overcook or shrimp will be dry and tough. Garnish if desired. Source: Cooking Class, Mexican Cookbook