Bring a large pot of salted water to a rolling boil and add spaghetti, stirring immediately so strands don't stick together. I always add salt before the pasta hits the water because that's your only chance to season it inside-out, not just on top. Cook until just al dente—one minute before the package says, since the pasta will finish cooking in the sauce.

While water heats, warm olive oil and butter together in a large skillet over medium-low heat. This matters because starting with cold butter and oil prevents garlic from burning—high heat is the biggest mistake I see people make here.

Once the butter foams, add minced garlic and stir constantly for exactly 60 seconds—no longer. Your nose will tell you when it's ready because the aroma shifts from raw and sharp to toasted and sweet. I count to sixty out loud because distraction costs you burnt garlic.

Pour in the heavy cream slowly, stirring as you go, then add salt, black pepper, and red pepper flakes. The reason for slow pouring is simple—rushing causes temperature shock and the sauce can break. Bring everything to a bare simmer and let it bubble gently for three minutes, which lets the flavors marry without scrambling the dairy.

Remove from heat and stir in both cheeses until completely melted and smooth, which takes about two minutes of constant stirring. This creamy garlic pasta crowd summer recipe sits here for a moment while you finish the pasta—timing's everything.

Drain pasta, reserving one cup of pasta water for adjusting sauce consistency if needed. Toss pasta into the skillet with sauce and add fresh lemon zest right at this moment, stirring gently for one minute until every strand coats evenly. The lemon transforms this from heavy to balanced.

Taste and adjust salt if needed—remember the pasta water was salted, so flavor compounds as you mix. Divide into bowls and finish each with a handful of fresh parsley, which adds color and a subtle herbaceous note.