Fill a large pot with water, add a generous pinch of salt, and bring it to a rolling boil. Add the linguine and cook according to package instructions until al dente, usually around 8-9 minutes. Once cooked, reserve about ½ cup of pasta water, then drain the pasta and set aside.
While the pasta is cooking, heat 2 tablespoons of unsalted butter in a large skillet over medium-high heat. Add the shrimp in a single layer, seasoning lightly with salt and pepper. Cook the shrimp for 2-3 minutes per side, or until they turn pink and opaque. Remove the shrimp from the skillet and set aside.
Reduce the heat to medium and add the remaining 2 tablespoons of butter to the same skillet. Once melted, add the minced garlic and red pepper flakes. Sauté for about 1 minute, or until fragrant but not burnt.
Return the cooked shrimp to the skillet along with the drained linguine. Toss everything together, adding reserved pasta water a little at a time to loosen the sauce to your desired consistency.
Turn off the heat and stir in freshly chopped parsley and the juice of one lemon. Taste and adjust seasoning with more salt and pepper if needed.
Dish out the Garlic Butter Shrimp Linguine onto plates, and if you like, sprinkle with grated Parmesan cheese for an extra layer of flavor. Serve immediately for best results.
