Special equipment: an oyster knife
Mix together the butter, parsley, white wine, garlic, shallots, 1/2 teaspoon salt and 1/4 teaspoon pepper in a bowl until thoroughly combined. Lay out a large piece of plastic wrap over a work surface and mound the butter mixture in the center. Fold the plastic over the butter and form into a log. Refrigerate until firm, at least 2 hours.
Set the oven broiler on medium-high heat.
Rinse the oysters in cold water and discard any open ones.
Shuck the oysters: Using a thick tea towel, hold an oyster firmly in one hand with the flat side facing up. With your other hand, insert an oyster knife into the oyster's hinge, easing it in where you can; make sure the hand holding the oyster is well protected by the towel. Once you feel the knife firmly anchored in the hinge, twist it to pop open the oyster. Clean your knife and then slide it along the top shell to release the muscle from the shell. Remove and discard the top shell. Run the knife under the oyster so the oyster is resting in the bottom shell but is no longer attached to it--this ensures the oyster will easily slide into your mouth when eaten. Discard any oysters that have an unpleasant odor.
Cover an oven-safe serving dish with a layer of rock salt. Gently nestle the shells into the salt so they won't slide around while broiling. Top each oyster with a slice of the compound butter. Broil until the butter is melted, golden and bubbling at the edges, 5 to 7 minutes.
Serve immediately with some crusty bread to soak up any leftover sauce.
If you have any leftover, the compound butter makes a great topping for beef or, of course, escargot!