Creamy Lobster Pasta with Truffle Infused Caviar and Chives

Name: Creamy Lobster Pasta with Truffle Infused Caviar and Chives
Ingredients: 6 lobster tails or 3 whole lobsters, blanched, meat picked and shells reserved; 4 cups (32 fl. oz./1 l) heavy cream; 1 yellow onion, peeled and halved through the root and stem; 4 unpeeled garlic cloves, crushed; Kosher salt and freshly ground pepper; 1 lb. (500 g) bucatini; 4 Tbs. (1/2 stick) (2 oz./60 g) unsalted butter; 1/3 cup (2 1/2 oz./75 g) crème fraîche, plus more for serving; 4 oz. (125 g) Parmesan cheese, grated; 1 jar (1 oz./28 g) Williams Sonoma Truffle Infused Caviar; 3 Tbs. minced fresh chives