1. Preheat the oven to 170°C (150° fan) | 325F | gas 3.
2. Bring a large saucepan of well-salted water to the boil. Add the spaghetti and cook until just 'al dente, ' about 8-9 minutes.
3. In the meantime, melt 1 tbsp butter in an ovenproof pan set over a moderate heat until hot. Add the bacon, frying until crispy, about 4-5 minutes. Set off the heat.
4. Whisk together the eggs, parmesan, 1/4 tsp salt, and 1/4 tsp black pepper in a mixing bowl. Stir in the bacon and any fat from the pan.
5. Drain the spaghetti when ready and add it to the pan with the remaining butter. Set over a medium heat, tossing until the butter is melted and the spaghetti is coated with it.
6. Pour in the egg mixture, carefully shaking the pan to evenly distribute the spaghetti and egg in an even layer.
7. Transfer to the oven, baking until just set and golden on top, about 25-30 minutes. Remove from the oven and let cool briefly.
8. When ready to serve, dress the rocket with the olive oil and some salt and pepper in a bowl, serving it on the side.