Spectacular double-cheese French onion soup

I've always loved onion soup, that classic dish from the French repertoire, not only because of its great taste, but also its ease of making and the fact it looks great! The other day, we experimented with the basic recipe, using a combination of cooking on stove-top and baking, to make something which looks spectacular and tastes fantastic. And it's all easily done with the addition of bread rolls!
Here's the drill:
To make the soup--Cut a large onion into thin half-moon slices. Fry in a little butter, add salt, pepper, herbs(your choice, but tarragon or thyme are our favourites). You can also add a little nutmeg. When onion is golden, add stock--chicken stock or vegetable stock, as you prefer.
Now get the bread roll ready--one for each person, this variety is served in individual dishes, as illustrated. Cut the (round and not too big) bread roll in three thin slices crosswise(as if cutting a cake in layers), to leave the top intact.
Pour the soup into ramekins or other individual dishes. Place a slice of bread on top of the soup. On this, sprinkle some crumbs of Roquefort, Gorgonzola or other blue cheese. Add the second slice of bread on top, and on it, grate some Gruyere or similar cheese. Place the top slice of the roll on top, finish with a mix of blue cheese and Gruyere. Bake in hot oven for around 5 minutes, till cheese is melted and bread is hot. Serve!