Prepare Shrimp: Pat the peeled and deveined shrimp very dry with paper towels. Season lightly with salt and pepper. Ensuring the shrimp are dry is crucial for a good sear and prevents the sauce from becoming watery. This initial seasoning helps build the flavor profile from the start.
Sauté Garlic: Melt 4 tablespoons of unsalted butter in a large skillet over medium-high heat. Add the minced garlic and red pepper flakes (if using). Sauté for about 30-60 seconds, until fragrant. Be careful not to burn the garlic, as burnt garlic can taste bitter and will spoil the dish's flavor.
Cook Shrimp: Add the seasoned shrimp to the skillet in a single layer. Cook for 1-2 minutes per side, or until the shrimp turn pink and opaque. Avoid overcrowding the pan; if necessary, cook the shrimp in two batches to ensure even cooking and a good sear. This is key to preventing rubbery shrimp.
Deglaze and Finish Sauce: Once the shrimp are cooked through, remove them from the skillet and set aside. Pour the white wine or chicken broth into the hot skillet, scraping up any browned bits from the bottom with a wooden spoon. Bring to a simmer and cook for 1-2 minutes, allowing the liquid to reduce slightly.
Combine and Serve: Return the cooked shrimp to the skillet. Add the remaining 2 tablespoons of butter, fresh parsley, and lemon juice. Toss everything together until the butter is melted and the shrimp are coated in the luscious garlic butter sauce. Serve immediately with your preferred sides, such as pasta or crusty bread.