Step 1Shell the shrimp, collecting the shells in a small deep saucepan; set the shrimp aside. Add the green onion and red bell pepper trimmings to the saucepan. Barely cover the shells and trimmings with water, about 3 to 3 1/2 cups, and bring to a simmer over medium heat. Cook 30 minutes, then remove from heat and let steep another 30 minutes. Sitr in one-half teaspoon salt and strain into a measuring cup. You should have about 3 cups of shrimp stock; what you don't use for this recipe can be stored tightly covered in the refrigerator.
Step 2Cut the zucchini in quarters lengthwise, then into crosswise slices about three-eighths-inch thick. You should have about 4 cups.
Step 3Cut the corn from the cobs by holding each cob upright in a wide, shallow bowl and cutting away the kernels with a sharp knife. Using the back of the knife, scrape any corn left on the cob into the bowl.
Step 4Melt the butter in a large skillet over medium heat. Add the chorizo and cook until well browned, about 8 to 10 minutes. Add the green onion and red bell pepper and cook until softened, about 5 minutes.
Step 5 Add the zucchini and shrimp and cook for a minute. Season with 2 teaspoons salt. Add the wine and raise the heat to high. Cook until the mixture is reduced to a syrup, about 5 minutes. Add the corn and one-half cup shrimp stock and let it reduce. Add another one-half cup stock and the whipping cream and cook just until slightly thickened and creamy, about 5 minutes.
Step 6Remove the pan from the heat and stir in the slivered basil. Taste and adjust seasoning and serve immediately.