Heat a large skillet or wide pan over medium heat and add the olive oil along with 2 tablespoons of the butter. Once the butter has melted and starts to gently foam, stir in the minced garlic. Sauté for about 30 seconds to 1 minute, just until the garlic becomes fragrant and lightly golden at the edges—take care not to let it brown too much, as it can turn bitter.
Add the shrimp to the pan in a single layer. Season lightly with salt and cracked black pepper. Cook the shrimp for 1–2 minutes on the first side, until they just begin to turn opaque and pink around the edges, then flip each piece.
Pour in the white wine (or broth) and sprinkle in the crushed red pepper flakes if using. Bring the mixture to a gentle simmer and let it bubble for 1–2 minutes, allowing the liquid to reduce by about half while the shrimp finish cooking through. The shrimp should be fully pink and slightly curved, but still tender—avoid overcooking so they stay juicy.
Remove the pan from the heat and immediately stir in the remaining 2 tablespoons of butter, the fresh lemon juice, and chopped parsley. Swirl the pan or gently stir until the butter melts into the sauce and everything is well combined, creating a glossy, garlicky lemon-butter coating over the shrimp.
Serve the shrimp scampi right away, spooning the sauce over the top. It’s excellent over hot pasta or fluffy rice, piled onto garlic bread, or served alongside steamed vegetables such as broccoli, cauliflower, or zucchini noodles for a lighter option.