Cook the spaghetti in a lot of water seasoned with a baby's handful of salt.
In a pan, warm half of the oil and add the onion, garlic, chili and broccoli top crumbs. Add the remaining ingredients and toss the drained spaghetti with the pesto. Feel free to squeeze a bit more lemon or drizzle some chili oil over the pasta to taste (which of course means I personally suggest this).