Cook fettuccine in a pasta pot of boiling salted water until al dente. Drain and set aside.
In a heavy skillet over medium-low heat, mix together the cream and butter and bring it to a gentle simmer. Add roughly 1/4 teaspoon salt and 1/2 teaspoon pepper (I typically do it to taste rather than measure, so this is an estimate). Dump in about half of the Parmigiano-Reggiano and whisk until the cheese is no longer stringy and is fully incorporated into the cream sauce. Repeat with second half of cheese. Add the champagne vinegar for a touch of acidity and add more salt to taste. Finally, throw in the cooked shrimp just long enough to heat through (don't over cook them!!) and remove the sauce from heat.
Toss the shrimp and sauce with the pasta and garnish with parsley.