Marinate the Shrimp: In a bowl, toss the cleaned shrimp with a pinch of salt, black pepper, half of the minced garlic, a drizzle of olive oil, and the red pepper flakes. Mix well and let the shrimp marinate for 10–15 minutes at room temperature. (This seasons the shrimp and infuses garlic flavor.)
Sear Shrimp: Heat a large skillet over medium-high heat. Add 1 tablespoon of olive oil and 2 tablespoons of butter. Once hot (but before the butter browns), add the shrimp in a single layer (work in batches if necessary). Sear the shrimp for about 1–2 minutes per side, just until they turn pink and are nearly cooked through. Remove shrimp to a plate and set aside.
Sauté Garlic: Reduce heat to medium. In the same skillet, add another 1 tablespoon of butter. Add the remaining minced garlic (and shallot, if using). Sauté for 30–60 seconds, stirring constantly until fragrant and just starting to turn light golden (do not burn the garlic).
Deglaze with Wine: Pour in the white wine and use a wooden spoon to scrape up any browned bits from the bottom of the pan. Bring to a simmer and let the wine cook down for about 2 minutes, reducing by roughly half.
Add Lemon: Stir in the fresh lemon juice and simmer for another 1 minute. Then turn off the heat and add the remaining 1 tablespoon of butter to the sauce, stirring until it melts and the sauce becomes silky. (This enriches and slightly thickens the sauce.)
Combine Shrimp and Sauce: Return the shrimp (along with any juices on the plate) to the skillet. Add the chopped parsley and lemon zest. Toss the shrimp in the sauce to coat. Turn the heat to medium-low and cook for about 1 minute, just to warm the shrimp through and let them finish cooking. Taste the sauce and season with additional salt and pepper if needed.
Serve: Serve the shrimp scampi immediately. Spoon the shrimp and plenty of sauce over cooked pasta, rice, or alongside crusty bread. Garnish with extra parsley and lemon wedges if desired. Enjoy!