Prep ingredients: Bring a large pot of salted water to a boil. Cover and keep warm over low heat. Peel and thinly slice 1 small garlic clove. Finely grate Parmesan. Pat shrimp dry. Cut pear in half, remove core and seeds, and cut into 8 wedges total. Pick parsley leaves from stems; discard stems and coarsely chop leaves.

Make glaze & cook pears: In a small saucepan, bring ¼ cup balsamic vinegar to a boil over high heat. Reduce heat to medium and simmer until liquid is reduced to 1 tablespoon, 5–6 minutes (watch closely). Transfer to a small bowl and let cool. Heat 1 tablespoon butter in a medium skillet until melted. Add pears, and cook, cut sides only, until lightly softened and browned, 2–5 minutes (depending on ripeness).

Wrap pears: Slice prosciutto in half lengthwise into 8 pieces total. Wrap a slice of prosciutto around each pear wedge. Transfer to small plates and cover with slightly damp paper towels.

Cook fettuccine: Return water to a boil. Add fettuccine in small handfuls. Cook, stirring frequently to prevent clumping until al dente, 10–12 minutes. Reserve 1 cup cooking water, then drain pasta, and return to pot; toss with 1 teaspoon butter.

Make Alfredo sauce: Heat 1 tablespoon butter in same skillet over medium until melted. Add sliced garlic and cook, stirring, until fragrant, about 1 minute. Add mascarpone and ½ cup of the reserved cooking water. Sprinkle in half of the grated Parmesan and stir to combine. Add shrimp and peas, remove skillet from heat and cover to keep warm.

Finish & serve: Drizzle balsamic glaze over pears, and serve. When ready to serve main course, add cooked pasta to skillet; cook over medium heat until shrimp are cooked through and pasta is coated in sauce, 2–3 minutes. Season to taste with salt and pepper. Serve pasta topped with parsley, remaining Parmesan, and freshly ground pepper.