Marinate the lamb. In a shallow dish or zip-top bag, combine the olive oil, garlic, rosemary, kosher salt, and black pepper. Add the lamb chops and toss until evenly coated. Let marinate at room temperature for 20–30 minutes (or refrigerate for up to 8 hours; bring to room temperature before cooking).

Make the lemon butter. In a small bowl, mash the softened butter with the lemon juice and lemon zest until smooth and fully combined. Set aside.

Preheat the grill or grill pan. Outdoor grill: Preheat to medium-high heat (400–450°F) and oil the grates well. Grill pan: Heat over medium-high until very hot; lightly brush with oil if needed.

Grill the lamb chops. Place the lamb chops on the grill or grill pan in a single layer (work in batches if needed). Grill for 3–4 minutes per side, until nicely charred and cooked to your desired doneness (about 130–135°F for medium-rare).

Rest and finish. Transfer the lamb chops to a serving platter and let rest for 5 minutes. Top each chop with a pat of lemon butter, allowing it to melt over the warm lamb.

Serve. Finish with flaky sea salt and serve immediately with lemon wedges on the side.