Bring a large pot of salted water to boil, then add fettuccine and cook until just barely al dente—about 2 minutes before the package says done. This matters because the pasta will finish in the sauce. Reserve one cup of pasta water before draining, which gives you control over the sauce consistency later.

While pasta cooks, melt butter and olive oil together in a large skillet over medium heat—never high heat, which burns the garlic into bitterness. Once the butter foams, add minced garlic and stir constantly for exactly 60 seconds until it smells sweet, then stop. I learned this by overcooking garlic three times and tasting the regret every time.

Pour heavy cream into the skillet with the garlic, reduce heat to medium-low, and let it simmer gently for 3–4 minutes while you watch it thicken slightly. Stir occasionally. The why here: this lets the garlic flavor infuse the cream without the cream breaking, because cream needs time, not heat.

Add Parmesan cheese in two additions, stirring between each pour until it melts completely and disappears into the sauce. Season with salt and 1/4 tsp black pepper, tasting as you go because Parmesan adds saltiness you can't unsalt later.

Stir in lemon juice now—after the cream has cooled slightly—which prevents the acid from curdling everything. The sauce should smell bright and garlicky without any heaviness in the aroma. Add red pepper flakes if you want heat, then fold in cooked shrimp gently so it stays tender.

Add drained fettuccine directly to the skillet and toss for 60 seconds, then add pasta water one splash at a time until the sauce coats each strand without pooling. This is where stunning creamy garlic pasta summer becomes either silky or too thick, so add water gradually and taste the difference between coated and drowning.

Remove from heat, scatter fresh parsley over the top, and serve immediately on warm plates. This step matters because parsley adds color that says "I didn't rush this," which changes how people taste it.