1. For the pangrattato,pulse the chunks of sourdough in a food processor to produce coarse breadcrumbs.
2. In a frying pan,combine the 60ml olive oil,chilli flakes and garlic on medium heat and stir for 1 minute before adding the breadcrumbs. Sauté for 5 minutes until the breadcrumbs are golden,add the parsley and sea salt,and remove from heat.
3. For the pasta,boil a large pot of salted water and cook spaghetti until al dente,according to instructions. Drain,reserving 100ml cooking water.
4. When the pasta has 3 minutes left to cook,combine the 100ml olive oil,garlic and chilli in a frying pan on medium heat until the garlic becomes fragrant;about 30 seconds to 1 minute.
5. Add the crab meat and gently stir before adding the wine and increasing the heat to cook it off. Add cooked spaghetti,butter,reserved pasta cooking water,lemon juice,parsley and sea salt. Stir well for a minute to allow the butter and water to emulsify. Remove from heat and divide between 4 bowls,garnishing with extra olive oil and a generous scattering of the pangrattato.