Preheat the oven to 200°C, fan 180°C, gas 6. Put the squash into a roasting tin and toss with olive oil, garlic cloves and black pepper. Bake in the oven for 30 minutes. Halfway through, scatter over the bacon and return to oven for the final 15 minutes. Remove and set aside. Reduce temperature to 180°C, fan 170°C, gas 4.
Meanwhile, put the spinach into a colander (or steamer) and steam over a pan of boiling water for 2-3 minutes, until wilted. Press with the back of a spoon to squeeze out any excess water.
In a bowl, combine the spinach with the ricotta and nutmeg and season well.
Remove the garlic cloves from the roasting tin. Carefully squeeze the soft garlic flesh out of the skins and stir into the butternut squash. Transfer the contents of the roasting tin to a large pan with the tomato and basil sauce and 150ml water. Stir and bring to the boil. Remove from heat and keep warm.
Cover the base of a baking dish with some of the butternut squash mixture, cover with one layer of lasagne and one layer of spinach and ricotta. Repeat until all the mixture has been used.
Top with torn mozzarella and bake for 30 minutes or until bubbling and golden.
Cook's tip: Place the wilted spinach in a large clean tea towel. Gather into a bag and twist the ends to squeeze out all of the spinach liquid.