Preheat the oven to 160° C w/ fan.
Cook the spaghetti for about 4-5 min (very al dente!), drain them & arrange the spaghetti in the oiled casserole.
Chop the bacon as well as the spring onions (rather finely!).
Proceed alike for the fresh thyme leaves & set aside.
Fry the bacon & the spring onions in olive oil for 4-5 min.
Distribute over the spaghetti layer.
Grate the Gruyère (roughly) & distribute over the bacon layer.
Grab an egg whisk & mix the crème fraîche w/ the eggs.
Add salt & pepper to taste.
Add the finely chopped fresh thyme leaves.
Pour the mix over everything & press slightly - try to cover the spaghetti layer w/ the egg mix.
Put it in the oven for about 40 min; the mix should become stiff.