Cook the spaghetti in a large saucepan of boiling water until al dente. Drain, return to pan and keep warm. Heat the oil in a non stick pan over medium heat.
Add the hazelnuts, chilli and garlic and cook for 3-4 minutes, stirring regularly.
Remove from heat, stir through parsley, lemon juice and season with salt and pepper to taste. Toss the hazelnut mixture through the pasta and serve.