Pat the shrimp very dry with paper towels — this is what gets you a sear instead of a steam. Toss with the salt and pepper. Melt 2 tablespoons of the butter in a large skillet over medium-high heat until foaming.

Arrange the shrimp in a single layer (work in two batches if crowded). Cook undisturbed 1 1/2–2 minutes per side, until pink, opaque, and curled into a loose C. Transfer to a plate — they should read 145°F on an instant-read thermometer at the thickest part.

Reduce the heat to medium. Add the remaining 3 tablespoons butter to the skillet with the sliced garlic and red pepper flakes (if using). Cook, stirring, until the garlic is pale gold and fragrant, about 30–60 seconds — don't let it brown.

Pour in the wine (or broth) and lemon juice, scraping up every browned bit from the bottom. Simmer 1–2 minutes, until reduced by about half.

Sprinkle in the Parmesan a handful at a time, stirring until each addition melts before adding the next. The sauce will turn glossy and lightly thickened. Taste and add salt if needed.

Return the shrimp and any juices to the skillet, tossing to coat in the sauce, 30–60 seconds until warmed through. Shower with parsley and extra Parmesan. Serve straight from the skillet with lemon wedges and crusty bread for soaking.