Add the butter and olive oil to a large chef's pan and heat until the butter melts and starts to foam.
Add the shallots, garlic, salt and sugar. Cook, stirring, over low heat for five minutes or until the shallots have softened.
Stir in the chopped tomatoes and cook for about a minute.
Add the wine and lemon juice and bring to a simmer. Increase the heat and cook for about five minutes or until the wine aroma disappears.
Add the brown crab meat and stir into the sauce.
Meanwhile cook the linguine while you prepare the sauce. Prepare according to packet instructions – cooked in salted water till al dente. Reserve about 120ml (1/2 cup) of the pasta water before draining.
Stir the pasta into the sauce and add the white crab meat and parmesan. Add a splash of the reserved pasta water to loosen the sauce.
Toss with the parsley to combine. Taste and adjust the seasoning, if needed. Serve with the parsley and chilli flakes.