Fill and boil your kettle. Peel the butternut squash, halve it lengthways and scoop out the seeds (you can keep them to roast for a snack, or pop them in your compost bin). Chop the squash into 1cm-thick cubes. Peel the red onions and thinly slice them. Peel and crush or finely chop the garlic. Pick the rosemary leaves and finely chop them. Chop the tomatoes into small chunks.

Slide all of the chopped ingredients into a large, heavy-based pan (a wide, shallow casserole dish is perfect). Season with a pinch of salt and pepper and drizzle in 2 tbsp olive oil. Crumble in the stock cube, pour in 1 ltr boiling water and stir well. Slide in the spaghetti (if you need to you can snap it in half to help it fit in the pan) and return to the boil. When boiling, turn the heat down low, cover with a lid – or a baking tray if you don’t have a lid – and cook for 20 mins, stirring every so often.

After 20 mins, the pasta should be tender and the sauce should have thickened. If not, cook for a few mins longer. Fold in the baby leaf spinach and squeeze in the juice from half the lemon. Stir everything together till the spinach is just wilted. Taste the pasta and add a pinch more salt or pepper if you think it needs it.

Scoop the pasta and sauce onto a couple of warm plates and serve with wedges of the remaining lemon half for squeezing.