Heat a little oil in a small sauté pan and gently fry the breadcrumbs until they start to turn a light golden brown. Drain and reserve.
Add a lug of olive oil to a medium sauté pan set over a medium heat, then add the butter. When the butter starts to bubble gently and foam (not brown), stir in the chilli, garlic and anchovy. Cook for a minute. Add the lemon zest and juice. Remove from the heat. Add the parmesan and sage and stir well. Keep warm.
Cook the pasta in boiling salted water according to the packet instructions. Drain, reserving some of the pasta cooking water.
Transfer the pasta to the buttery lemon sauce along with a lug of pasta water. Return to the heat and toss the pasta with the sauce using a spoon or tongs, ensuring that all the pasta is coated and the sauce is rich and reduced. Season with a little more salt and black pepper, then serve immediately sprinkled with the breadcrumbs.