- Place macaroni in a large microwaveable bowl and cover with water.
- Add a pinch of salt and cover with clingfilm.
- Microwave for 10-12 minutes on high or until cooked through, stopping to stir every few minutes.
- Drain into a colander, rinse with cold water and set aside.
- Melt butter in a microwaveable mug on high for 20 seconds, check and microwave again for 10-20 seconds if needed.
- Whisk melted butter and flour together in a large microwaveable bowl.
- Add milk and whisk mixture well to remove any lumps.
- Microwave for 3-5 minutes, whisking at 1-minute intervals, until you have a thick sauce.
- Add mustard and salt and pepper.
- Add cooked macaroni, cheese and spring onion or herbs to the sauce and mix through.
- Microwave for another 3-5 minutes.
- Spoon mac ’n cheese into four bowls or mugs and serve immediately.