Boil the pasta: Bring a large pot of salted water to a rolling boil. Add the pasta and cook until al dente according to the package instructions. Before draining, reserve at least 1/2 cup of pasta water.

Melt the butter: In a large skillet over medium heat, melt the butter. Let it foam gently but avoid browning if you want a pure butter flavor. If you love nutty notes, let it go a touch longer until golden and fragrant.

Cook the garlic: Add the minced garlic to the melted butter. Stir frequently and cook for 30–60 seconds, just until fragrant. Do not let it brown, or it can turn bitter.

Add heat if you like: Stir in red pepper flakes for a subtle warmth. This is optional but adds nice depth.

Create the sauce: Pour in 1/4 cup of reserved pasta water and whisk or stir vigorously. You’ll see the butter and starchy water come together into a glossy sauce.

Toss the pasta: Add the drained pasta directly to the skillet. Toss to coat thoroughly, adding more pasta water a spoonful at a time until the sauce clings to the pasta and looks silky.

Season and finish: Taste and add salt and freshly ground pepper. Stir in parsley and a squeeze of lemon juice or a pinch of zest if using. If you like, sprinkle with Parmesan just before serving.

Serve immediately: Garlic butter sauce is best hot and fresh. Twirl into bowls and serve right away.