Melt 1 tablespoon butter in a large skillet over medium high heat. Remove the small side muscle from the scallops, rinse with cold water and thoroughly pat dry. Season scallops with salt and pepper, to taste. Working in batches, add scallops to the skillet in a single layer and cook, flipping once, until golden brown and translucent in the centre, about 1-2 minutes per side. Set aside and keep warm.
To make the lemon butter sauce, melt 2 tablespoons butter in the skillet. Add garlic and cook, stirring frequently, until fragrant, about 1 minute. Stir in lemon juice; season with salt and pepper, to taste. Serve scallops immediately with lemon butter sauce, garnished with parsley, if desired.