Preheat oven to 375°F. Slice the top off the garlic head, drizzle with olive oil and a pinch of salt, wrap in foil, and roast for 60 minutes until soft and caramelized.
To a food processor, add butter, roasted garlic, parsley, shallot, nutmeg, caper juice, champagne vinegar, lemon zest, and black pepper. Blend until smooth. Taste and adjust seasoning as needed.
Remove the tough foot from each scallop. Pat scallops dry with paper towels.
Add a small spoonful of escargot butter to the bottom of each oven-safe shell. Top with a scallop, season with salt and pepper, and finish with another dollop of escargot butter.
Place on a sheet pan and broil on high (middle rack) for 6-7 minutes until scallops are just cooked and butter is bubbling.
Finish with fresh lemon zest and juice. Serve hot with crusty French bread to soak up every drop.