FoFa says:
"Here is a pretty easy recipe, but takes awhile to cook the onions. We use this as a side dish rather than a main dish. I like both yellow or red onions for this dish."
2 eggs, well beaten
4 large Spanish onions, peeled and thinly sliced
4 T butter
1/4 cup freshly grated Parmesan cheese
salt & freshly ground black pepper
l lb spaghetti cooked
Melt butter in a saucepan.
Add the onions, some salt and a couple tablespoons of cold water.
Cover and simmer over very low heat until onions have softened to the point of being puree-like, about 20 to 30 minutes. Make sure onions do not dry out. Add water by the teaspoon as needed.
Meanwhile cook the pasta.
Towards the end of the pasta cooking time, mix the beaten eggs and mix with the onions and keep warm.
Drain pasta, reserving a 1/4 cup the cooking water in case you need to thin the sauce a little.
Place pasta in a warm bowl and pour on the onion sauce with a few grinds of the pepper mill and combine well.
Use Parmesan at table.