Peel and de-vein (if necessary) the shrimp. Keep the peeled shrimp in a bowl of ice water until ready to use.
Melt 2 tablespoons of butter in a large sauté pan over medium-high heat. Pat the shrimp dry with a paper towel and season lightly with salt and pepper. Working in batches, add the shrimp to the pan, making sure to leave a little space between each so they cook evenly.Cook the shrimp for 1-2 minutes on each side until they are just barely pink and the heads and tails are curled toward each other. Transfer the cooked shrimp to a bowl. Repeat with the remaining shrimp, adding more butter to the pan as needed, and set aside. If needed, add another tablespoon of butter and oil to the same pan. Sauté the shallots over medium heat until slightly softened, about 3-4 minutes. Add the garlic and cook for another minute until it becomes aromatic.
Add the wine, lemon juice, and tomatoes to the pan. Bring the mixture to a boil, then reduce the heat and let it simmer for about 8-10 minutes until nearly all the liquid has evaporated. You should be able to slide a wooden spoon across the bottom of the pan without the liquid immediately pooling back.
Add 1 cup of cream to the mixture and stir well to combine. In a small bowl, whisk together the remaining 1 cup of cream and the cornstarch until smooth. Add this slurry and the Parmesan cheese to the pan, stirring until the sauce is well combined and starts to thicken. If you prefer a thinner sauce, add more cream or milk. If you wish to thicken the sauce, add some reserved pasta water. Return the shrimp, along with any juices in the bowl, to the pan. Cook until the edges start to bubble and the shrimp is cooked through, about 2-3 minutes. Add the sauce to the cooked pasta, along with the fresh herbs, cayenne pepper (optional), and salt and pepper to taste. Mix until everything is well combined and serve. Garnish with fresh parsley and parmesan cheese.