If using a stick blender, put the anchovies into a bowl with the garlic and lemon juice and blitz to a paste. Still blitzing, gradually pour in a third of the oil, and when that’s absorbed ...
Cook gently until the anchovies have melted into a paste. Add the chilli flakes and mix well. Reduce the heat to low until the pasta is ready. When the pasta is two minutes away from being ready ...