Make the Creole butter: combine butter, Creole seasoning, Worcestershire, and parsley flakes in a small bowl. Mix thoroughly. Spoon the butter onto a sheet of wax paper and form into a log, twisting the ends to seal. Put in the refrigerator while everything else cooks.
Preheat the oven to 400°. Cover a large sheet pan with parchment or foil.
Wash potatoes and pat dry. If very tiny, leave whole and pierce each one with the point of a paring knife. If a few are larger than the rest, cut those in half. If using larger potatoes, cut in fairly even 1½-inch chunks. Put the potatoes in a bowl and toss with olive oil, salt and pepper. Spread the potatoes in a single layer on the sheet pan. Set the oily bowl aside.
Slice the sausage about ½ inch thick on the diagonal. Add the sliced sausage to the sheet pant with the potatoes, also in a single layer. Put the pan in the oven for 20 minutes.
Meanwhile, cut the stem and tassel ends off the ears of corn. Do not shuck the corn yet. Put the ears of corn in the microwave for 3½ minutes. As soon as it's cool enough to handle, shuck the corn. (Notice how easy it is to get the silk off!) Cut each ear into thirds and set aside.
While the corn is cooking, pat shrimp dry and put in the oily bowl you used to toss the potatoes. drizzle a little more olive oil and season with salt and pepper. Toss the shrimp to coat.
When the potatoes and sausage have cooked 20 minutes, check the potatoes with a sharp paring knife--they should pierce easily even if they aren't quite as cooked as you want them. Add the shrimp and corn to the pan. You can nestle the corn anywhere, but make sure the shrimp is in a single layer. Return the pan to the oven and continue to cook for 10 minutes.
Serve hot with generous pats of Creole butter.