Steps
1. Heat the butter in a pan over medium-high heat.
2. Add the onions and sauté for 3-4 minutes until the onions are beginning to soften.
3. Add the ketchup to the pan and mix everything together.
4. Add the cooked pasta and stir until everything is evenly combined.
5. Cook for a further 3 minutes, stirring occasionally.
6. Serve and enjoy!