Boil a salted pot of water and cook the pasta al dente according to package directions.
Add butter to a skillet over medium heat. Once melted, cook the garlic for about 1 minute.
Add the tomatoes, Italian seasoning, lemon juice and zest, Dijon mustard, and cream. Stir until smooth, then let it simmer for about 5 minutes or until the tomatoes start to soften/fall apart.
In a small bowl, mix the cornstarch with 1 teaspoon of cold water and stir it into the skillet.
Add the crab and parmesan to the sauce and cook it for a few minutes until it's warmed through and the sauce has thickened up a bit.
If the sauce gets too thick, reserve some of the hot pasta water and add it to the sauce.
Once the pasta is cooked, drain it, add it to the skillet, and toss it with the sauce. Season with salt & pepper as needed, and sprinkle with the chopped parsley. Serve with extra grated parmesan cheese if desired.