In a saucepan bring 6 cups of water to a boil. Using a small paring knife, remove the vein along the back of each shrimp and rinse under running water. Add garlic to water and boil for two minutes. Add the shrimp to the water and cook with the garlic for 2-3 minutes. Drain the shrimp and garlic. Peel the garlic and finely chop. Heat oil in a large skillet over medium heat. Add garlic and cook for 1 minute. Pour in heavy cream and bring to a simmer. Cook until cream begins to thicken. Stir in parsley, Parmesan and shrimp. Season with salt and pepper. Pour sauce over linguine in a large bowl and toss to coat. Garnish with parsley and Parmesan.