Grab your shears and snip the top of each lobster tail, cutting through some meat. Flip and crack the shell open gently with your thumbs.
Loosen the flesh, remove the vein (if present), and lay it back on the shell, open-faced.
Whip up a marinade with parsley, garlic, Dijon, olive oil, lemon juice, a pinch of salt, and a dash of pepper.
Preheat your oven to broil (high heat) and position the rack for distance from the broiler.
Place butterflied tails in a dish, brush with marinade, and dot with butter pieces.
Broil for 10-11 minutes (adjust based on size) until lobster meat is opaque white (145°F internal temp).
Drain pan drippings, add remaining butter, simmer, and drizzle over lobster or serve for dipping.