Cook the Pasta: Bring a large pot of salted water to a rolling boil. Add the spaghetti and cook according to package directions until al dente (usually around 8-10 minutes). Just before draining, reserve about 250ml (a mugful) of the starchy pasta water. Drain the pasta in a colander.

Sauté the Prawns: While the pasta is cooking, heat the olive oil and 1 tablespoon of the butter in a large frying pan or skillet over medium-high heat. Once the butter is foaming, add the prawns in a single layer. Season with salt and pepper. Cook for 1-2 minutes per side, just until they turn pink and opaque. Do not overcook them. Remove the prawns from the pan with a slotted spoon and set them aside on a plate.

Build the Garlic Sauce: Reduce the heat to medium-low. Add the remaining 2 tablespoons of butter to the same pan. Once melted, add the thinly sliced garlic and the red pepper flakes. Sauté gently for about 1-2 minutes, stirring constantly, until the garlic is fragrant and softened but not browned. Burnt garlic will make the sauce bitter.

Deglaze the Pan: Pour in the dry white wine to deglaze the pan, scraping up any tasty browned bits from the bottom with a wooden spoon. Let it simmer and reduce by about half, which should take about 2-3 minutes.

Create the Emulsified Sauce: Add about 120ml of the reserved starchy pasta water to the pan, along with the lemon juice and zest. Bring to a simmer and let it bubble away for a minute. The starches in the pasta water will help thicken the sauce and make it glossy. I find that whisking it a little at this stage helps it come together beautifully.

Combine Everything: Add the drained pasta directly into the pan with the sauce. Toss everything together vigorously with tongs for about a minute until the pasta is well-coated. Add the cooked prawns and the chopped fresh parsley to the pan.

Finish and Serve: Toss everything together one last time. If the sauce looks a little too thick, add another splash of the reserved pasta water until it reaches your desired consistency. Taste and adjust seasoning with more salt and pepper if needed. Serve immediately, topped with a little extra parsley and grated Parmesan cheese if you like.