Put the kettle on, as you will need to add boiling water to your pot when adding the pasta, or have a pot of boiling water on the go.
Meanwhile, heat the olive oil in a large heavy-based saucepan over high heat. Add the garlic, spring onion and chilli and toss until the garlic starts to become golden and fragrant. Add the pasta, the mussels and the capers, enough boiling water to submerge the pasta. Start stirring gently - the sauce will thicken ever so slightly as the orecchiette soak up all juices. Cook for 8 minutes or until perfectly al dente.
Remember that the residual heat will continue cooking the pasta when you turn off the heat, so it's always a good idea to keep it very al dente. Turn off the heat, then scatter over the reserved spring onion, drizzle an little olive oil and eat straight away.