Roast the pumpkin (200C for about 20-40 minutes until tender) and soak pasta in a little boiling water to soften a little. Crush the pumpkin with a fork, adding 2 tbsp of the olive oil if there aren't sufficient juices to keep it moist. Leave it a little chunky, you don't want it too smooth.
In a large frying pan melt the butter over a med to high heat. Add the garlic, stir and add spinach leaves until they wilt. Add them a handful at a time to prevent stewing. Season and drain in a colander. Transfer to a mixing bowl, add the feta and 1 tbsp of grated cheese (parmesan or cheddar). Mix well.
Cover bottom of lasagna dish with pasta sheets, top with a layer of pumpkin, top with a 2nd layer of pasta, then the spinach and cheese mixture. Put on the 3rd layer of pasta followed by more pumpkin then the final layer of pasta. Make a basic white sauce and pour over the top then sprinkle with a little more parmesan Cook in a medium oven until brown on top, about 20 minutes. Serve hot.
Melt the butter in a small saucepan and stir in the flour. Cook, stirring continuously, for 1 minute, until the mixture forms a smooth ‘roux’.
Remove the pan from the heat and gradually pour in the milk, stirring or whisking constantly. Return the pan to the heat and bring to the boil, still stirring or whisking.
Reduce the heat and simmer the white sauce gently for 2 minutes, stirring occasionally, until it is smooth and thick. Season to taste with salt and pepper.