Peel sweet potatoes and cut them into cubes of about 1 cm. Peel and finely dice the onion. Peel garlic and chop finely. Cook the spaghetti in plenty of boiling salted water (approx. 1 teaspoon salt per litre) according to the instructions on the packet.
Heat the oil in a frying pan. Fry the sweet potatoes for 6-8 minutes until golden brown. Fry onion and garlic for about 3 minutes. Season with salt, pepper and nutmeg. Add cream, milk and goat's cheese and let it boil down to a creamy consistency.
Sort the spinach, wash and drain. Drain the pasta, collecting 50 ml of pasta water. Mix the noodles and pasta water in the pan with the sweet potato mix and the spinach. Season with salt and pepper and serve immediately.