Warm the pot: Place a large, heavy-bottomed pot over medium heat. Add olive oil and butter, letting the butter melt and foam slightly.

Sauté the garlic: Stir in the garlic and cook for 30–60 seconds until fragrant. Do not brown it; browned garlic can taste bitter. Lower the heat if needed.

Add the liquid: Pour in the broth. Bring it to a gentle boil. Taste the broth and season lightly with salt and pepper; remember the Parmesan later will add saltiness.

Add the pasta: Drop the pasta straight into the simmering broth. If using long noodles, press them down as they soften so they’re fully submerged. Stir to separate strands and prevent sticking.

Simmer and stir: Cook uncovered at a lively simmer, stirring every minute or two. Keep the pasta moving so it cooks evenly and releases starch into the liquid. This usually takes 8–10 minutes, depending on shape and brand.

Adjust the liquid if needed: If the pot looks dry before the pasta is al dente, add hot water or a splash more broth, 1/4 cup at a time. You want a little liquid left before adding cream.

Stir in the cream: Lower the heat to medium-low. Pour in the heavy cream and stir until the sauce begins to thicken and coat the pasta, 1–2 minutes.

Add Parmesan: Remove the pot from heat. Stir in the Parmesan until melted and smooth. If using lemon zest and red pepper flakes, add them now. Taste and adjust salt and pepper.

Rest briefly: Let the pasta sit for 1–2 minutes. The sauce will thicken further as it stands. If it gets too thick, loosen with a splash of warm water or broth.

Finish and serve: Sprinkle with chopped parsley or chives. Twirl into bowls and top with extra Parmesan and a crack of black pepper. Serve hot.