Shrimp étouffée is made the exact same way as my crawfish étouffée recipe here, except you use shrimp instead of crawfish. If you're starting with cooked shrimp, you only need to heat them in the sauce until they are heated through. If you're starting with raw shrimp, you're going to want to cook them in the sauce until they are pink and fully cooked through. This should only take a few minutes.