Bring a large pot of salted water to a boil. Cook the pasta to two minutes less than package instructions. Drain and reserve 1 cup pasta water.
Meanwhile, cook the crab. Whisk the first 5 ingredients together on a plate. Dredge each crab in the flour mixture and shake off the excess. Heat the butter in a pan over high heat and add the crabs, top side down. Cook for 3 minutes and then flip; cook for an additional 3-4 minutes until crabs are red and coating is golden and crispy. Remove from pan and set aside.
In the same pan, make the sauce. Add the olive oil, garlic and shallot and cook for 1-2 minutes; until fragrant and starting to soften. Add the tomatoes and season them with salt and pepper. Cook until tomatoes have burst; about 7-10 minutes.
Add the drained pasta to the pan and toss to coat. Add pasta water as needed to loosen the sauce.
Roughly chop two of the cooked crabs and add it to the pan with the pasta. Reserve the remaining two for the top of the pasta. Garnish with parsley and chives. Serve with lemon wedges.