Bring a large sauté pan to medium-high heat and add oil to coat the bottom. Add garlic cloves and fry until golden to infuse them in the oil. Once cooked, remove cloves and discard. Add crayfish and cook until they turn bright red. Add half of the flat leaf parsley and red pepper flakes, if desired. Add both cans of tomatoes and mix well.
Cook pasta in salted, boiling pot of water. When done, pour sauté mixture over pasta and add the remaining parsley.